Immunoglobulin E and Its Effects on Respiratory Tract and Upper Airways

Immunoglobulin E (IgE) is a type of antibody that provides immunity against microorganisms like Trichinella spiralis and Schistosoma mansoni that attack the body (Monroe, 2001). In addition, IgE plays an important role in providing immune protection to the body against protozoan microorganisms like Plasmodium falciparum. Another role of IgE is evident from its action during type I hypersensitivity. Type I hypersensitivity is observed in allergic diseases such as allergic rhinitis and asthma (Monroe, 2001). In addition, it is observed in allergic reactions such as food allergy, atopic dermatitis, and chronic urticaria. The role played by IgE in allergic reactions is immense and important. For example, it plays a pivotal role in anaphylactic reactions that occur due to the reaction of the body to certain drugs and antigen solutions. Despite its low concentrations in blood, IgE possesses the ability to trigger very strong inflammatory reactions that result in symptoms such as incessant sneezing, mucous production, and constriction of airways (Thurmond, 2011).

An allergic reaction refers to a disorder of the immune system that occurs due to the body’s reaction to a harmless substance (Monroe, 2001). A substance that causes such a reaction is referred to as an allergen. Allergy is among the many forms of hypersensitivity reactions that are elicited by the immune system. Allergic reactions are characterized by extreme activation of mast cells and basophils by an antibody known as IgE. Allergic reactions result in inflammatory responses that have several symptoms. Allergic rhinitis causes inflammation of the nasal airways due to an allergic reaction. The reaction is elicited when an individual who possesses a sensitive immune system inhales an allergen. After inhalation, the allergen triggers the secretion of IgE (Thurmond, 2011). The IgE binds to mast cells and basophils that contain histamine. Histamine is an inflammatory mediator that causes incessant sneezing, swelling of the nasal passage, and mucous production. After the release of histamine by mast cells and basophils, the permeability of cells of the respiratory tract and upper airways increase. This facilitates the entry of blood fluids such as leukocytes into the blood vessels thus causing swelling. Histamine induces phosphorylation of VE-cadherin that increases the permeability of the cells of the respiratory tract and upper airways (Monroe, 2001). This consequently triggers the release of cytokines and other inflammatory mediators that increase inflammatory responses.

Histamine also causes constriction of airways by initiating constriction of smooth muscles. As a result, muscles that surround the airways contract thus causing shortness of breath. Production of mucous is caused by the body’s immune response to foreign substances in the body (Thurmond, 2011). The mucous is produced to get rid of allergens that cause inflammatory reactions. Histamines stimulate goblet cells to produce mucus in order to create a fluid environment that facilitates the removal of allergens from the body (Denburg, 1998). In asthmatic patients, the airways overproduce mucously and increase the risk of asthma attacks. On the other hand, sneezing occurs due to irritation of nerve cells. The passage of allergens through the nasal passage triggers the production of histamine that irritates nasal nerve cells (Thurmond, 2011). This results in the transmission of signals to the brain through the trigeminal nerve network. The brain then initiates sneezing by initiating the opening of nasal and oral cavities through the activation of the muscles of the trachea and pharyngeal (Denburg, 1998). Sneezing results in the release of allergens and other bioparticles from the body.

References

Denburg, J. (1998). Allergy and Allergic Diseases: The New Mechanisms and Therapeutics. New York: Humana press.

Monroe, J. (2001). Allergies. New York: Capstone.

Thurmond, R. (2011). Histamine in Inflammation. New York: Springer.