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Allergies Causes

Allergies: Causes


Top Causes

1. Type III reactions

These allergic reactions mostly occur when there is a little amount of antibody and excess antigen in the blood leading to the formation of small immune complexes that are not cleared off by the circulation. Although, they do not exhibit symptoms as that of type I reactions, they tend to get deposited in tissues and induce an inflammatory response, and cause damage wherever possible.

2. Fur and hair

It is most common that many individuals exhibit a strong sense of allergic reaction to cat fur. The mode of reaction is once again IgE mediated and the common methods of testing include the radio-allergen sorbent test, which identifies an individualโ€™s sensitivity to a wide range of allergic proteins including cat fur and hair.

3. Pollen

One of the most studied allergen, pollen is believed to elicit an allergic response in many individuals who are sensitive to the pollen grains, which could have been transmitted by genetic means or frequent exposure to pollen is also capable of inducing an IgE mediated allergic response such as rhinitis.

4. House mites

A common component of dust is one of the primary factors that leads to the development of allergies of different kinds in humans. House mites lead to the excessive production of IgE, which in turn cross link the mast cells that are released in the process of inflammatory response. The binding of antigen to the IgE, which in turn has cross linked with the IgE-receptors on the surface of the mast cell, leads to the release of various cytokines that lead to the manifestation of allergy in individuals.

5. Parasites

Gutworms and other types of parasites, both ecto- and endo- are important risk factors for allergy in humans. The surface proteins lead to the excitation and the release of a wide range of inflammatory cytokines such as the TNF-alpha, Interferon-gamma, interleukin-10 and -12 from the leukocytes that circulate in the blood. However, prior exposure to these endotoxins may reduce the inflammatory reaction, thus leading to less septic shock.

6. Toxins that react with various proteins

Certain non-food proteins such as those exhibited by the poison ivy, western and eastern poison oak, or the poison sumac cause T-cell mediated immune reactions. Hypersensitivity is of type IV, unlike the conventional type I reactions, which are more common in individuals. Urushiol is a common protein and a hapten that chemically reacts with the integral membrane proteins that are present on the cell surface, thus leading to the development of an allergic reaction. The dermatological response includes redness, papules, blisters, swelling, streaking, and formation of vesicles.

7. Hygiene factors

It is well known that allergic reactions are also caused due to inappropriate responses to a vast deal of harmless antigens that elicit a TH2-mediated immunological response in humans. Many such bacteria and viruses are believed to develop a TH1-response that regulates the TH2-response. The hygiene hypothesis states that a lack of sufficient stimulation of the TH1-response is said to induce a TH2-response, which in turn leads to allergic diseases. Thus, it implies that individuals who survive in an extremely sterile environment are not sufficiently exposed to pathogens and, hence, are likely to develop an allergic reaction when compared to individuals who are exposed.

8. Genetics

The risk and the development of allergic sensitization vary with age and the genetic makeup of an individual. Many studies have proven that IgE levels are greater in childhood and tend to rapidly decrease with increasing age. It is also believed that the likelihood of developing allergies is related to the DNA that determines the sensitivity to a specific allergen. Ethnicity may also play a major role in a few allergies; however, racial factors are difficult to separate from environmental factors. The placement of the genetic loci also plays a major role in asthma, an outcome of allergic reaction, especially in people of Hispanic, Asian, European, and African origins.

9. Non-proteins

Certain elements such as latex are also believed to trigger IgE-mediated allergic reactions, which have a prominent cutaneous, respiratory and systemic manifestation. Although, the prevalence of such latex-induced reactions are less than one percent of the total population. The sensitivity to latex is observed highest amongst health care workers who are frequently exposed to the usage of latex. The mode of reaction is same as that of food-borne allergens and the outcome is mostly itching and urticaria.

10. Food

This is one of the most common causes of allergies. It has been observed that many individuals demonstrate sensitivity and allergic reaction to peanuts and other types of seeds, such as sesame and poppy seeds, that contain a mix of oil and protein elicit allergic reaction in many individuals. Egg and lactose allergies (lactose intolerance) are believed to affect about two percent of the children who are below the age of five years. The sensitivity is usually demonstrated to the protein albumin rather than the yolk. Beef also contains considerable amount of allergic protein, which elicits an allergic response in many individuals. The allergen proteins induce the stimulation of IgE, a type of antibody that is involved in such reactions, thus establishing an allergic reaction in individuals.

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