With more than 25 percent of the world’s population reportedly suffering from allergic-reaction related conditions, allergy is increasingly becoming one of the world’s widespread conditions. Oft marked with a characteristic features such as itching, sneezing and vasodilatation, an allergy, according to Ahmed (2011), is an overreaction of an individual’s immune system to a substance (allergen) which does not usually cause any reaction to other people. Such an overreaction occurs when the body recognizes a substance as foreign thereby inducing an immune response marked with the production of antibodies.
Mechanism of an Allergic Reaction
An allergic response, as affirmed by Ahmed (2011), can conveniently be divided in to two phases broadly referred to as the Sensitization phase marked with the production of IgE antibody and the reactivation phase marked with the mast cells and basophils releasing their contents that are the cause of various allergenic reaction related conditions like inflammation in the body as a result of a reexposure to the former antigen.
During sensitization phase, the immune system captures and processes allergens that come into contact with the immune system for the first time with the help of Antigen Presenting Cells commonly abbreviated as APC. The processed allergens are then taken to the lymph nodes to be presented to B and T cells. This is then followed by the differentiation of the T-cells into several subpopulations, which together with other antigenic stimulus signalize the B lymphocytes to produce IgE antibodies releasing them in to the blood stream (Ahmed, 2011). IgE (Immunoglobulin E) antibodies are a special type of immunoglobulin with the ability to trigger some of the most serious immunological reactions in a human body. Coico & Sunshine (2009), while asserting that all normal human beings have the ability to produce IgE antibodies specific for a variety of allergens also concur that the IgE antibody is the antibody that role plays largely in all allergenic reactions. It noteworthy that there are several types if T cells such as helper, memory, regulatory and cytotoxic; the T-helper cells (abbreviated Th-cell is the one that is greatly involved during allergic reactions). The IgE antibodies released in to the blood stream rapidly attach on the surface membranes of mast cells and basophils (as a result of binding with the specific receptors found on the surface of the mast cells and basophils) resulting in the sensitization of the cells (Ahmed, 2011). It should be noted that the sensitization phase does not result into any allergy-related symptom.
Reactivation phase, results from a subsequent reexposure to a similar allergen prompting the previously sensitized mast cells and basophils to release the contents their granules (Ahmed, 2011; Coico & Sunshine, 2009) though a process that Bloemen et al. (2007) refers to as degranulation. Mast cells and basophils degranulate to produce histamine, heparin, serotonin, and proteases as well as others like leukotrienes and prostaglandins that are collectively called mediators. It is these mediators that are responsible for the showcasing of the allergic symptoms.
Difference between a Normal and an Allergic Person
Why some people are allergic to certain substances while others are not still remains a misery to scientists. However, the difference between an allergic person and normal person can be explained in terms of the specificity of IgE. As mentioned earlier, different IgEs are specific to different allergens. Different people experience different IgE-mediated hypersensitivity (atopy) while others do not experience IgE-mediated hypersensitivity at all. The cause of IgE-mediated hypersensitivity is yet to be discovered. Concisely, allergic people are different from nonallergic people in the sense that allergic people experience IgE-mediated hypersensitivity while nonallergic people do not.
References
Ahmed, N. (2011). Clinical Biochemistry. New York, NY: Oxford University Press.
Bloemen, K., Verstraelen, S., Van Den Heuvel, R., Witters, H., Nelissen, I., & Schoeters, G. (2007). The Allergic Cascade: Review of the Most Important Molecules in the Asthmatic Lung. Immunology Letters, 113; 3-18. doi:10.1016/j.imlet.2007.07.010
Coico, R., & Sunshine, G. (2009). Immunology: A Short Course. New Jersey: John Wiley and Sons.
