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83-700: Allergies , also known as allergic diseases , are various conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever , food allergies , atopic dermatitis , allergic asthma , and anaphylaxis . Symptoms may include red eyes , an itchy rash , sneezing , coughing , a runny nose , shortness of breath , or swelling. Note that food intolerances and food poisoning are separate conditions. Common allergens include pollen and certain foods. Metals and other substances may also cause such problems. Food, insect stings , and medications are common causes of severe reactions. Their development

166-502: A TH2 -mediated immune response. Many bacteria and viruses elicit a TH1 -mediated immune response, which down-regulates TH2 responses. The first proposed mechanism of action of the hygiene hypothesis was that insufficient stimulation of the TH1 arm of the immune system leads to an overactive TH2 arm, which in turn leads to allergic disease. In other words, individuals living in too sterile an environment are not exposed to enough pathogens to keep

249-424: A "second skin" effect. Synthetic latices are used in coatings (e.g., latex paint) and glues because they solidify by coalescence of the polymer particles as the water evaporates. These synthetic latices therefore can form films without releasing potentially toxic organic solvents in the environment. Other uses include cement additives and to conceal information on scratchcards . Latex, usually styrene -based,

332-528: A T helper 2 (TH2)-predominant response driven by suppression of interleukin 12 by both the autonomic nervous system and the hypothalamic–pituitary–adrenal axis . Stress management in highly susceptible individuals may improve symptoms. Allergic diseases are more common in industrialized countries than in countries that are more traditional or agricultural, and there is a higher rate of allergic disease in urban populations versus rural populations, although these differences are becoming less defined. Historically,

415-439: A better protection to the plant from enemies than all the thorns, prickles, or hairs that could be provided. In this plant, so copious and so distasteful has the sap become that it serves a most important purpose in its economy. Evidence showing this defense function include the finding that slugs will eat leaves drained of their latex but not intact ones, that many insects sever the veins carrying latex before they feed, and that

498-406: A branching system extending throughout the plant. In many euphorbs , the entire structure is made from a single cell – this type of system is known as a non-articulated laticifer , to distinguish it from the multi-cellular structures discussed above. In the mature plant, the entire laticiferous system is descended from a single cell or group of cells present in the embryo . The laticiferous system

581-409: A country grows more affluent and, it is presumed, cleaner. The use of antibiotics in the first year of life has been linked to asthma and other allergic diseases. The use of antibacterial cleaning products has also been associated with higher incidence of asthma, as has birth by caesarean section rather than vaginal birth. Chronic stress can aggravate allergic conditions. This has been attributed to

664-410: A cytotoxic, cell-mediated, delayed hypersensitivity reaction involving T cells . The first three types are considered immediate hypersensitivity reactions because they occur within 24 hours. The fourth type is considered a delayed hypersensitivity reaction because it usually occurs more than 12 hours after exposure to the allergen, with a maximal reaction time between 48 and 72 hours. Hypersensitivity

747-524: A hitherto unsuspected symbiosis is at work. For more information on this topic, see Helminthic therapy . In the initial stages of allergy, a type I hypersensitivity reaction against an allergen encountered for the first time and presented by a professional antigen-presenting cell causes a response in a type of immune cell called a T H 2 lymphocyte , a subset of T cells that produce a cytokine called interleukin-4 (IL-4). These T H 2 cells interact with other lymphocytes called B cells , whose role

830-425: A large local reaction may occur in the form of an area of skin redness greater than 10 cm in size that can last one to two days. This reaction may also occur after immunotherapy . Risk factors for allergies can be placed in two broad categories, namely host and environmental factors. Host factors include heredity , sex, race , and age, with heredity being by far the most significant. However, there has been

913-405: A latex allergy. Latex-fruit syndrome Many people with latex allergy also experience allergic reactions to certain fruits. This association has led to research regarding latex-fruit syndrome (LFS). This is a phenomenon characterized by cross-reactivity between natural latex rubber allergens and certain fruit allergens, leading to allergic reactions in sensitized individuals. It was described for

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996-449: A licensed health care provider ( e.g. , an allergy specialist) or general practitioner. Unlike skin-prick testing, a blood test can be performed irrespective of age, skin condition, medication, symptom, disease activity, and pregnancy. Adults and children of any age can get an allergy blood test. For babies and very young children, a single needle stick for allergy blood testing is often gentler than several skin pricks. An allergy blood test

1079-531: A lower-allergen substitute. Additionally, chemical processes may be employed to reduce the amount of antigenic protein in Hevea latex, yielding alternative materials such as Vytex Natural Rubber Latex which provide significantly reduced exposure to latex allergens. About half of people with spina bifida are also allergic to natural latex rubber. People who have had multiple surgeries and who have had prolonged exposure to natural latex are also more susceptible to

1162-415: A milk allergy will have a reaction to beef. Lactose intolerance, a common reaction to milk, is not a form of allergy at all, but due to the absence of an enzyme in the digestive tract . Those with tree nut allergies may be allergic to one or to many tree nuts , including pecans , pistachios , and walnuts . In addition, seeds , including sesame seeds and poppy seeds , contain oils in which protein

1245-578: A molecular weight ranging from 10 to 40 kDa. The response to the antigen occurs in two stages: the sensitization and the effect stage. In the "sensitization" stage, the host experiences an asymptomatic contact with the antigen. Subsequently, in the "effect" period, the pre-sensitized host is re-introduced to the antigen, which then leads to a type I anaphylactic or atopic immune response. Type II hypersensitivity reaction refers to an antibody-mediated immune reaction in which antibodies (IgG or IgM) are directed against cellular or extracellular matrix antigens with

1328-423: A patient in for evaluation, some allergists will prefer an initial blood test prior to performing the skin prick test. Skin tests may not be an option if the patient has widespread skin disease or has taken antihistamines in the last several days. Patch testing is a method used to determine if a specific substance causes allergic inflammation of the skin. It tests for delayed reactions. It is used to help ascertain

1411-445: A process called degranulation , during which they release histamine and other inflammatory chemical mediators ( cytokines , interleukins , leukotrienes , and prostaglandins ) from their granules into the surrounding tissue causing several systemic effects, such as vasodilation , mucous secretion, nerve stimulation, and smooth muscle contraction. This results in rhinorrhea , itchiness, dyspnea, and anaphylaxis. Depending on

1494-566: A product of an emulsion , mini-emulsion, micro-emulsion, or dispersion polymerization . The cells ( laticifers ) in which latex is found make up the laticiferous system, which can form in two very different ways. In many plants, the laticiferous system is formed from rows of cells laid down in the meristem of the stem or root . The cell walls between these cells are dissolved so that continuous tubes, called latex vessels, are formed. Since these vessels are made of many cells, they are known as articulated laticifers . This method of formation

1577-439: A recent increase in the incidence of allergic disorders that cannot be explained by genetic factors alone. Four major environmental candidates are alterations in exposure to infectious diseases during early childhood, environmental pollution , allergen levels, and dietary changes. Dust mite allergy, also known as house dust allergy, is a sensitization and allergic reaction to the droppings of house dust mites . The allergy

1660-504: A series of immune-mediated events that might take different forms. In type III hypersensitivity reaction, an abnormal immune response is mediated by the formation of antigen-antibody aggregates called "immune complexes". They can precipitate in various tissues such as skin, joints, vessels, or glomeruli, and trigger the classical complement pathway. Complement activation leads to the recruitment of inflammatory cells (monocytes and neutrophils) that release lysosomal enzymes and free radicals at

1743-608: A systematic classification of the different types of hypersensitivity based on the types of antigens and immune responses involved. According to this system, known as the Gell and Coombs classification or Gell-Coombs's classification, there are four types of hypersensitivity, namely: type I , which is an Immunoglobulin E (IgE) mediated immediate reaction; type II , an antibody-mediated reaction mainly involving IgG or IgM ; type III , an immune complex-mediated reaction involving IgG , complement system and phagocytes ; and type IV ,

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1826-434: A systemic allergic response that is also called anaphylaxis; multiple organ systems can be affected, including the digestive system , the respiratory system , and the circulatory system . Depending on the severity, anaphylaxis can include skin reactions, bronchoconstriction, swelling , low blood pressure , coma, and death. This type of reaction can be triggered suddenly, or the onset can be delayed. The nature of anaphylaxis

1909-425: Is inherited and related to an irregularity in the immune system, but the specific allergen is not. The risk of allergic sensitization and the development of allergies varies with age, with young children most at risk. Several studies have shown that IgE levels are highest in childhood and fall rapidly between the ages of 10 and 30 years. The peak prevalence of hay fever is highest in children and young adults and

1992-443: Is a common occurrence: it is estimated that about 15% of humans have at least one type during their lives, and has increased since the latter half of the 20th century. The Gell and Coombs classification of hypersensitivity is the most widely used, and distinguishes four types of immune response that result in bystander tissue damage. Type I hypersensitivity occurs as a result of exposure to an antigen. The antigens are proteins with

2075-541: Is a complex emulsion that coagulates on exposure to air, consisting of proteins , alkaloids , starches , sugars , oils , tannins , resins , and gums . It is usually exuded after tissue injury. In most plants, latex is white, but some have yellow, orange, or scarlet latex. Since the 17th century, latex has been used as a term for the fluid substance in plants, deriving from the Latin word for "liquid". It serves mainly as defense against herbivorous insects . Latex

2158-429: Is a significant allergy to the substance in question. Early exposure of children to potential allergens may be protective. Treatments for allergies include avoidance of known allergens and the use of medications such as steroids and antihistamines . In severe reactions, injectable adrenaline (epinephrine) is recommended. Allergen immunotherapy , which gradually exposes people to larger and larger amounts of allergen,

2241-489: Is actively moved to the area of injury; in the case of Cryptostegia grandiflora , latex more than 70 cm from the site of injury is mobilized. The large hydrostatic pressure in this vine enables an extremely high flow rate of latex. In a 1935 report the botanist Catherine M. Bangham observed that "piercing the fruit stalk of Cryptostegia grandiflora produced a jet of latex over a meter long, and maintained [this jet] for several seconds." The clotting property of latex

2324-469: Is also used in immunoassays . Some people only experience a mild allergy when exposed to latex, with symptoms such as eczema , contact dermatitis , or developing a rash . Others have a serious latex allergy , and exposure to latex products such as latex gloves can cause anaphylactic shock . Guayule latex has only 2% of the levels of protein found in Hevea latices, and it is being researched as

2407-805: Is an allergic contact dermatitis, a delayed hypersensitive reaction appearing as dry, crusted lesions. This reaction usually lasts 48–96 hours. Sweating or rubbing the area under the glove aggravates the lesions, possibly leading to ulcerations. Anaphylactic reactions occur most often in sensitive patients who have been exposed to a surgeon's latex gloves during abdominal surgery, but other mucosal exposures, such as dental procedures, can also produce systemic reactions. Latex and banana sensitivity may cross-react. Furthermore, those with latex allergy may also have sensitivities to avocado , kiwifruit, and chestnut. These people often have perioral itching and local urticaria . Only occasionally have these food-induced allergies induced systemic responses. Researchers suspect that

2490-485: Is available through most laboratories . A sample of the patient's blood is sent to a laboratory for analysis, and the results are sent back a few days later. Multiple allergens can be detected with a single blood sample. Allergy blood tests are very safe since the person is not exposed to any allergens during the testing procedure. Hypersensitivity In 1963, Philip George Houthem Gell and Robin Coombs introduced

2573-399: Is common and can trigger allergic reactions such as asthma, eczema , or itching .The mite's gut contains potent digestive enzymes (notably peptidase 1 ) that persist in their feces and are major inducers of allergic reactions such as wheezing . The mite's exoskeleton can also contribute to allergic reactions. Unlike scabies mites or skin follicle mites, house dust mites do not burrow under

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2656-499: Is due to both genetic and environmental factors. The underlying mechanism involves immunoglobulin E antibodies (IgE), part of the body's immune system, binding to an allergen and then to a receptor on mast cells or basophils where it triggers the release of inflammatory chemicals such as histamine . Diagnosis is typically based on a person's medical history . Further testing of the skin or blood may be useful in certain cases. Positive tests, however, may not necessarily mean there

2739-474: Is found in the poppy family and in the rubber trees ( Para rubber tree , members of the family Euphorbiaceae , members of the mulberry and fig family , such as the Panama rubber tree Castilla elastica ), and members of the family Asteraceae . For instance, Parthenium argentatum the guayule plant, is in the tribe Heliantheae ; other latex-bearing Asteraceae with articulated laticifers include members of

2822-455: Is functional in this defense since it limits wastage and its stickiness traps insects and their mouthparts. While there exist other explanations for the existence of latex including storage and movement of plant nutrients, waste, and maintenance of water balance that "[e]ssentially none of these functions remain credible and none have any empirical support". The latex of many species can be processed to produce many materials. Natural rubber

2905-759: Is mediated by T cells that provoke an inflammatory reaction against exogenous or endogenous antigens. In certain situations, other cells, such as monocytes, eosinophils, and neutrophils, can be involved. After antigen exposure, an initial local immune and inflammatory response occurs that attracts leukocytes. The antigen engulfed by the macrophages and monocytes is presented to T cells, which then becomes sensitized and activated. These cells then release cytokines and chemokines, which can cause tissue damage and may result in illnesses. Examples of illnesses resulting from type IV hypersensitivity reactions include contact dermatitis and drug hypersensitivity. Type IV reactions are further subdivided into type IVa, IVb, IVc, and IVd based on

2988-538: Is not itself a protein, acts as a hapten and chemically reacts with, binds to, and changes the shape of integral membrane proteins on exposed skin cells. The immune system does not recognize the affected cells as normal parts of the body, causing a T-cell -mediated immune response . Of these poisonous plants, sumac is the most virulent. The resulting dermatological response to the reaction between urushiol and membrane proteins includes redness, swelling, papules , vesicles , blisters , and streaking. Estimates vary on

3071-432: Is not to be confused with plant sap ; it is a distinct substance, separately produced, and with different functions. The word latex is also used to refer to natural latex rubber , particularly non- vulcanized rubber. Such is the case in products like latex gloves , latex condoms , latex clothing , and balloons . Latex : Colloidal dispersion of polymer particles in a liquid. Synthetic latex : Latex obtained as

3154-452: Is often guided by relevant literature. In general, a positive response is interpreted when the wheal of an antigen is ≥3mm larger than the wheal of the negative control (eg, saline or glycerin). Some patients may believe they have determined their own allergic sensitivity from observation, but a skin test has been shown to be much better than patient observation to detect allergy. If a serious life-threatening anaphylactic reaction has brought

3237-451: Is often the practice for determining whether allergy to milk, egg, soy, and wheat have been outgrown, and the testing interval is extended to 2–3 years for allergy to peanut, tree nuts, fish, and crustacean shellfish. Results of follow-up testing can guide decision-making regarding whether and when it is safe to introduce or re-introduce allergenic food into the diet. Skin testing is also known as "puncture testing" and "prick testing" due to

3320-595: Is present in all parts of the mature plant, including roots, stems, leaves , and sometimes the fruits . It is particularly noticeable in the cortical tissues. Latex is usually exuded as a white liquid, but is some cases it can be clear, yellow or red, as in Cannabaceae . Latex is produced by 20,000 flowering plant species from over 40 families . These include both dicots and monocots . Latex has been found in 14 percent of tropical plant species, as well as six percent of temperate plant species. Several members of

3403-417: Is present, which may elicit an allergic reaction. Allergens can be transferred from one food to another through genetic engineering ; however, genetic modification can also remove allergens. Little research has been done on the natural variation of allergen concentrations in unmodified crops. Latex can trigger an IgE-mediated cutaneous, respiratory, and systemic reaction. The prevalence of latex allergy in

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3486-509: Is presumed, exposed to more infectious agents through their siblings, than in children from families with only one child. It is used to explain the increase in allergic diseases that have been seen since industrialization, and the higher incidence of allergic diseases in more developed countries. The hygiene hypothesis has now expanded to include exposure to symbiotic bacteria and parasites as important modulators of immune system development, along with infectious agents. Epidemiological data support

3569-417: Is production of antibodies. Coupled with signals provided by IL-4, this interaction stimulates the B cell to begin production of a large amount of a particular type of antibody known as IgE. Secreted IgE circulates in the blood and binds to an IgE-specific receptor (a kind of Fc receptor called FcεRI ) on the surface of other kinds of immune cells called mast cells and basophils , which are both involved in

3652-466: Is saline or glycerin; positive is histamine). A small plastic or metal device is used to puncture or prick the skin. Sometimes, the allergens are injected "intradermally" into the patient's skin, with a needle and syringe. Common areas for testing include the inside forearm and the back. If the patient is allergic to the substance, then a visible inflammatory reaction will usually occur within 30 minutes. This response will range from slight reddening of

3735-455: Is severe laryngeal edema. Treatment of type 4 HR involves the treatment of the eliciting cause. peripheral: Purine nucleoside phosphorylase deficiency Latex Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latices are found in nature , but synthetic latices are common as well. In nature, latex is found as a milky fluid , which is present in 10% of all flowering plants (angiosperms). It

3818-450: Is such that the reaction can seem to be subsiding but may recur throughout a period of time. Substances that come into contact with the skin, such as latex , are also common causes of allergic reactions, known as contact dermatitis or eczema. Skin allergies frequently cause rashes , or swelling and inflammation within the skin, in what is known as a " weal and flare" reaction characteristic of hives and angioedema . With insect stings,

3901-447: Is termed an "allergic" reaction (which usually refers to type I hypersensitivity), its pathophysiology involves a reaction that more correctly corresponds to a type IV hypersensitivity reaction. In type IV hypersensitivity, there is activation of certain types of T cells (CD8+) that destroy target cells on contact, as well as activated macrophages that produce hydrolytic enzymes . Effective management of allergic diseases relies on

3984-496: Is the most important product obtained from latex; more than 12,000 plant species yield latex containing rubber, though in the vast majority of those species the rubber is not suitable for commercial use. This latex is used to make many other products including mattresses , gloves , swim caps , condoms , catheters and balloons . Dried latex from the opium poppy is called opium , the source of several useful analgesic alkaloids such as codeine , thebaine , and morphine ,

4067-536: Is useful for some types of allergies such as hay fever and reactions to insect bites. Its use in food allergies is unclear. Allergies are common. In the developed world, about 20% of people are affected by allergic rhinitis, about 6% of people have at least one food allergy, and about 20% have or have had atopic dermatitis at some point in time. Depending on the country, about 1–18% of people have asthma. Anaphylaxis occurs in between 0.05–2% of people. Rates of many allergic diseases appear to be increasing. The word "allergy"

4150-482: Is usually to proteins in the white , rather than the yolk . Milk-protein allergies —distinct from lactose intolerance —are most common in children. Approximately 60% of milk-protein reactions are immunoglobulin E –mediated, with the remaining usually attributable to inflammation of the colon . Some people are unable to tolerate milk from goats or sheep as well as from cows, and many are also unable to tolerate dairy products such as cheese. Roughly 10% of children with

4233-483: The Cichorieae , a clade whose members produce latex, some of them in commercially interesting amounts. This includes Taraxacum kok-saghyz , a species cultivated for latex production. In the milkweed and spurge families, on the other hand, the laticiferous system is formed quite differently. Early in the development of the seedling, latex cells differentiate, and as the plant grows these latex cells grow into

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4316-500: The lungs , shortness of breath , coughing, and wheezing. Aside from these ambient allergens, allergic reactions can result from foods, insect stings , and reactions to medications like aspirin and antibiotics such as penicillin . Symptoms of food allergy include abdominal pain, bloating , vomiting, diarrhea , itchy skin, and hives . Food allergies rarely cause respiratory (asthmatic) reactions, or rhinitis . Insect stings, food, antibiotics , and certain medicines may produce

4399-1003: The ability to make an accurate diagnosis. Allergy testing can help confirm or rule out allergies. Correct diagnosis, counseling, and avoidance advice based on valid allergy test results reduce the incidence of symptoms and need for medications, and improve quality of life. To assess the presence of allergen-specific IgE antibodies, two different methods can be used: a skin prick test, or an allergy blood test . Both methods are recommended, and they have similar diagnostic value. Skin prick tests and blood tests are equally cost-effective, and health economic evidence shows that both tests were cost-effective compared with no test. Early and more accurate diagnoses save cost due to reduced consultations, referrals to secondary care, misdiagnosis, and emergency admissions. Allergy undergoes dynamic changes over time. Regular allergy testing of relevant allergens provides information on if and how patient management can be changed to improve health and quality of life. Annual testing

4482-505: The acute inflammatory response. The IgE-coated cells, at this stage, are sensitized to the allergen. If later exposure to the same allergen occurs, the allergen can bind to the IgE molecules held on the surface of the mast cells or basophils. Cross-linking of the IgE and Fc receptors occurs when more than one IgE-receptor complex interacts with the same allergenic molecule and activates the sensitized cell. Activated mast cells and basophils undergo

4565-474: The antigen-antibody complexes are pre-formed in the circulation before their deposition in tissues. Type IV hypersensitivity reactions are, to some extent, normal physiological events that help fight infections, and dysfunction in this system can predispose to multiple opportunistic infections. Adverse events can also occur due to these reactions when an undesirable interaction between the immune system and an allergen happens. A type IV hypersensitivity reaction

4648-533: The blood. Certain microbe-sensing proteins , known as Toll-like receptors , found on the surface of cells in the body are also thought to be involved in these processes. Parasitic worms and similar parasites are present in untreated drinking water in developing countries, and were present in the water of developed countries until the routine chlorination and purification of drinking water supplies. Recent research has shown that some common parasites, such as intestinal worms (e.g., hookworms ), secrete chemicals into

4731-403: The cause of skin contact allergy or contact dermatitis . Adhesive patches, usually treated with several common allergic chemicals or skin sensitizers, are applied to the back. The skin is then examined for possible local reactions at least twice, usually at 48 hours after application of the patch, and again two or three days later. An allergy blood test is quick and simple and can be ordered by

4814-676: The cross-reactivity of latex with banana, avocado , kiwifruit , and chestnut occurs because latex proteins are structurally homologous with some other plant proteins. About 10% of people report that they are allergic to penicillin ; however, of that 10%, 90% turn out not to be. Serious allergies only occur in about 0.03%. One of the main sources of human allergies is insects. An allergy to insects can be brought on by bites, stings, ingestion, and inhalation. Another non-food protein reaction, urushiol-induced contact dermatitis , originates after contact with poison ivy , eastern poison oak , western poison oak , or poison sumac . Urushiol , which

4897-482: The delayed establishment of gut flora in infants . However, the research to support this theory is conflicting, with some studies performed in China and Ethiopia showing an increase in allergy in people infected with intestinal worms. Clinical trials have been initiated to test the effectiveness of certain worms in treating some allergies. It may be that the term 'parasite' could turn out to be inappropriate, and in fact

4980-710: The first time by Blanco et al. in 1994. In a 2024 comprehensive review by Gromek et al., the last 30 years of research on LFS were summarized, focusing on its prevalence, common cross-reactions, and clinical manifestations. The review found that the prevalence of LFS in latex-allergic patients varies widely, ranging from 4% to 88%, depending on diagnostic methods, geographical regions, and study populations. The most commonly implicated fruits in LFS include banana, avocado, kiwifruit, and papaya. Clinical manifestations are predominantly systemic, with 73% of hypersensitivity symptoms being systemic and 27% localized. Gromek et al. also highlighted

5063-447: The fungal kingdom also produce latex upon injury, such as Lactarius deliciosus and other milk-caps . This suggests it is the product of convergent evolution and has been selected for on many separate occasions. Latex functions to protect the plant from herbivores. The idea was first proposed in 1887 by Joseph F. James, who noted that latex of milkweed carries with it at the same time such disagreeable properties that it becomes

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5146-587: The general population is believed to be less than one percent. In a hospital study, 1 in 800 surgical patients (0.125 percent) reported latex sensitivity, although the sensitivity among healthcare workers is higher, between seven and ten percent. Researchers attribute this higher level to the exposure of healthcare workers to areas with significant airborne latex allergens, such as operating rooms, intensive-care units, and dental suites. These latex-rich environments may sensitize healthcare workers who regularly inhale allergenic proteins. The most prevalent response to latex

5229-464: The gut wall (and, hence, the bloodstream) that suppress the immune system and prevent the body from attacking the parasite. This gives rise to a new slant on the hygiene hypothesis theory—that co-evolution of humans and parasites has led to an immune system that functions correctly only in the presence of the parasites. Without them, the immune system becomes unbalanced and oversensitive. In particular, research suggests that allergies may coincide with

5312-459: The hygiene hypothesis. Studies have shown that various immunological and autoimmune diseases are much less common in the developing world than the industrialized world, and that immigrants to the industrialized world from the developing world increasingly develop immunological disorders in relation to the length of time since arrival in the industrialized world. Longitudinal studies in the third world demonstrate an increase in immunological disorders as

5395-461: The immune system busy. Since our bodies evolved to deal with a certain level of such pathogens, when they are not exposed to this level, the immune system will attack harmless antigens, and thus normally benign microbial objects—like pollen—will trigger an immune response. The hygiene hypothesis was developed to explain the observation that hay fever and eczema , both allergic diseases, were less common in children from larger families, which were, it

5478-493: The incidence of asthma is highest in children under 10. Ethnicity may play a role in some allergies; however, racial factors have been difficult to separate from environmental influences and changes due to migration . It has been suggested that different genetic loci are responsible for asthma, to be specific, in people of European , Hispanic , Asian , and African origins. Allergic diseases are caused by inappropriate immunological responses to harmless antigens driven by

5561-458: The individual, allergen, and mode of introduction, the symptoms can be system-wide (classical anaphylaxis) or localized to specific body systems. Asthma is localized to the respiratory system and eczema is localized to the dermis . After the chemical mediators of the acute response subside, late-phase responses can often occur. This is due to the migration of other leukocytes such as neutrophils , lymphocytes , eosinophils , and macrophages to

5644-439: The initial site. The reaction is usually seen 2–24 hours after the original reaction. Cytokines from mast cells may play a role in the persistence of long-term effects. Late-phase responses seen in asthma are slightly different from those seen in other allergic responses, although they are still caused by release of mediators from eosinophils and are still dependent on activity of T H 2 cells. Although allergic contact dermatitis

5727-411: The latex of Asclepias humistrata (sandhill milkweed ) kills by trapping 30% of newly hatched monarch butterfly caterpillars. Other evidence is that latex contains 50–1000× higher concentrations of defense substances than other plant tissues. These toxins include ones that are also toxic to the plant and consist of a diverse range of chemicals that are either poisonous or " antinutritive. " Latex

5810-441: The latter two of which can then further be used in the synthesis and manufacture of other (typically stronger) opioids for medicinal use, and of heroin for the illegal drug trade . The opium poppy is also the source of medically useful non-analgesic alkaloids, such as papaverine and noscapine . Latex is used in many types of clothing . Worn on the body (or applied directly by painting), it tends to be skin-tight , producing

5893-413: The most common food allergy in adults or children. Severe or life-threatening reactions may be triggered by other allergens and are more common when combined with asthma. Rates of allergies differ between adults and children. Children can sometimes outgrow peanut allergies. Egg allergies affect one to two percent of children but are outgrown by about two-thirds of children by the age of 5. The sensitivity

5976-418: The need for standardized diagnostic criteria and severity grading systems to improve the accuracy of LFS diagnosis and treatment. Several species of the microbe genera Actinomycetes , Streptomyces , Nocardia , Micromonospora , and Actinoplanes are capable of consuming rubber latex. However, the rate of biodegradation is slow, and the growth of bacteria utilizing rubber as a sole carbon source

6059-424: The number of CD4 cells, they also have a defective type four hypersensitivity reaction. The treatment of immediate hypersensitivity reactions includes the management of anaphylaxis with intramuscular adrenaline (epinephrine), oxygen, intravenous (IV) antihistamine, support blood pressure with IV fluids, avoid latex gloves and equipment in patients who are allergic, and surgical procedures such as tracheotomy if there

6142-491: The population fraction that will have an immune system response. Approximately 25% of the population will have a strong allergic response to urushiol. In general, approximately 80–90% of adults will develop a rash if they are exposed to 0.0050 mg (7.7 × 10 gr) of purified urushiol, but some people are so sensitive that it takes only a molecular trace on the skin to initiate an allergic reaction. Allergic diseases are strongly familial ; identical twins are likely to have

6225-567: The resultant cellular destruction, functional loss, or damage to tissues. The antigens may be for example glycoproteins on the cell membrane of erythrocytes that are key molecules that determine blood types. Depending on the chemical nature of the antigens, blood types have different levels of hypersensitivity; for instance, A and B are more antigenic than other antigens. Damage can be accomplished via three different mechanisms: The pathophysiology of type II hypersensitivity reactions can be broadly classified into three types: The process involves

6308-477: The same allergic diseases about 70% of the time; the same allergy occurs about 40% of the time in non-identical twins . Allergic parents are more likely to have allergic children and those children's allergies are likely to be more severe than those in children of non-allergic parents. Some allergies, however, are not consistent along genealogies ; parents who are allergic to peanuts may have children who are allergic to ragweed . The likelihood of developing allergies

6391-408: The series of tiny punctures or pricks made into the patient's skin. Tiny amounts of suspected allergens and/or their extracts ( e.g. , pollen, grass, mite proteins, peanut extract) are introduced to sites on the skin marked with pen or dye (the ink/dye should be carefully selected, lest it cause an allergic response itself). A negative and positive control are also included for comparison (eg, negative

6474-415: The site of immune complexes, causing tissue damage. The most common diseases involving a type III hypersensitivity reaction are serum sickness, post-streptococcal glomerulonephritis, systemic lupus erythematosus, farmers' lung (hypersensitivity pneumonitis), and rheumatoid arthritis. The principal feature that separates type III reactions from other hypersensitivity reactions is that in type III reaction,

6557-533: The skin and are not parasitic. A wide variety of foods can cause allergic reactions, but 90% of allergic responses to foods are caused by cow's milk, soy , eggs, wheat, peanuts, tree nuts , fish, and shellfish. Other food allergies, affecting less than 1 person per 10,000 population, may be considered "rare". The most common food allergy in the US population is a sensitivity to crustacea . Although peanut allergies are notorious for their severity, peanut allergies are not

6640-435: The skin to a full-blown hive (called "wheal and flare") in more sensitive patients similar to a mosquito bite . Interpretation of the results of the skin prick test is normally done by allergists on a scale of severity, with +/− meaning borderline reactivity, and 4+ being a large reaction. Increasingly, allergists are measuring and recording the diameter of the wheal and flare reaction. Interpretation by well-trained allergists

6723-546: The trees planted in urban areas were predominantly male to prevent litter from seeds and fruits, but the high ratio of male trees causes high pollen counts, a phenomenon that horticulturist Tom Ogren has called " botanical sexism ". Alterations in exposure to microorganisms is another plausible explanation, at present, for the increase in atopic allergy . Endotoxin exposure reduces release of inflammatory cytokines such as TNF-α , IFNγ , interleukin-10 , and interleukin-12 from white blood cells ( leukocytes ) that circulate in

6806-402: The type of T cell (Th1, Th17, and CTLs) involved and the cytokines/chemokines produced. Delayed hypersensitivity plays a crucial role in our body's ability to fight various intracellular pathogens such as mycobacteria and fungi. They also play a principal role in tumor immunity and transplant rejection. Since patients with acquired immunodeficiency syndrome ( AIDS ) have a progressive decline in

6889-411: Was first used by Clemens von Pirquet in 1906. Many allergens such as dust or pollen are airborne particles. In these cases, symptoms arise in areas in contact with air, such as the eyes, nose, and lungs. For instance, allergic rhinitis, also known as hay fever, causes irritation of the nose, sneezing, itching, and redness of the eyes. Inhaled allergens can also lead to increased production of mucus in

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