Pathophysiology
Exposure to environmental allergens such as pollen and grasses elicit immediate hypersensitivity reactions (hypersensitivity type I). This type of allergic reaction is primarily mediated by immunoglobulin E (IgE) (Aljabban et al., 2019). Other immune cells such as B and T cells are also involved in eliciting the immune responses. Effector T cells produce cytokines that promote the cell-mediated immune responses and the production of antigen-specific IgE by B-cells. The main T-cell subtype involved is TH2. Inhalation of the allergen results in the sensitization of the immune cells. Antigen-presenting cells (APC) process the allergen and then migrate to the lymph nodes for priming of the TH cells, which then differentiate into the cytokine-producing subsets. Interleukin 5 (IL-5) mediates the development, recruitment, and activation of eosinophils, while IL-9 mediates the recruitment and activation of mast cells. Production of antigen-specific IgE antibodies by B cells is by antibody class switching mediated by IL-4 and IL-13. B cells bind to the TH2 cells through the CD40 ligand surface. They also bind to the antigen, process it and present the allergen peptides through the MHC class II molecules on their surface which are recognized by the TH2 cells (Aljabban et al., 2019; Bernstein, D., Schwartz, & Bernstein, J., 2016). Subsequent exposure to the allergen results in cross-linking of the IgE antibodies on basophils and mast cells. This cascade culminates in the production and release of chemical mediators such as histamine, chemotactic factors, proteoglycans, leukotrienes, and cyclooxygenase products (Aljabban et al., 2019).
Clinical Manifestations
Anaphylaxis is the pathophysiologic reaction to an allergen. This is often characterized by difficulty in breathing resulting from bronchoconstriction or angioedema of the pharyngeal tissue. The patient may also experience spontaneous respiratory or circulatory collapse, which may predispose to anaphylactic shock. Other clinical manifestations are allergic rhinoconjunctivitis in which the patient experiences a runny nose and watery eyes, sneezing, coughing, sore throat, and itching of the palate (Seidan et al., 2015).
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Treatment and Care Plan
Effective treatment and management of immediate-type hypersensitivity reaction involve four interventions. These are immunotherapy, pharmacotherapy, allergen avoidance, and surgical therapy in advanced cases. Patient education is imperative before the initiation choosing the intervention approach and initiation of therapy (Wallace et al., 2017). It is important for the patient to understand the etiology and risk factors of their condition.
Allergen Avoidance
The patient should be made aware that he is allergic to pollen and grasses. Exposure to pollen and grass elicits an immune response which is responsible for the presenting symptoms. The body’s immune cells recognize the allergens as foreign molecules and therefore initiates mechanisms to counter them. It is important to determine the history and pattern of the patient’s condition, i.e., whether it is seasonal or perennial. This can be determined through the patient’s recollection. The patient may recall where he was before the onset of the symptoms, or which season of the year, the symptoms occur. This aids in the avoidance of subsequent exposure and thus lessen the symptoms ( Small, Keith, & Kim, 2018; Wallace et al., 2017). For example, if the symptoms began after visiting a countryside ranch, recovery may be hastened and future symptoms prevented.
Pharmacologic Intervention :
This includes the administration of antihistamines, glucocorticoids, and decongestants. The drugs are aimed at suppressing the immune reaction and thus exacerbating the symptoms. Nasal spray glucocorticoids are preferred because they have relatively few side effects. The possible side effects of nasal sprays are drying of the nasal mucosa, unpleasant smell or taste, irritation, and bleeding of the nasal septum. The sprays are indicated for relieving nasal congestion (Wallace et al., 2017).
Antihistamines are prescribed to relieve runny nose, sneezing, itching, and allergic rhinitis. They, however, are ineffective in relieving nasal congestion. The patient should be aware that antihistamines may result in sedation and should, therefore, be cautious when using them. Combination therapy of antihistamines and nasal decongestants may be administered for optimum results (Wallace et al., 2017; Wheatley, & Togias, 2015).
Immunologic interventions
This approach involves altering the patient’s immune responses to the allergens. Allergen immunotherapy against pollen alters the body’s immune response cascade against pollen. The changes may be gradual, but will eventually result in fewer or no clinical symptoms on future exposure to the allergens. The treatment involves several months of weekly injections and can be costly for the patient (Scadding et al., 2017; Durham, & Penagos, 2016). Given the long duration required for completion of the therapy, patient compliance is highly encouraged.
References
Aljabban, J., McDermott, S., Wanner, R. A., Salhi, H., Aljabban, N., Mukhtar, M., ... & Hadley, D. (2019). Meta-analysis Illustrates the Genetic Signature Underlying Allergic Rhinitis Pathophysiology and Potential Therapeutic Targets. Journal of Allergy and Clinical Immunology , 143 (2), AB185.
Bernstein, D. I., Schwartz, G., & Bernstein, J. A. (2016). Allergic rhinitis: mechanisms and treatment. Immunology and Allergy Clinics , 36 (2), 261-278.
Durham, S. R., & Penagos, M. (2016). Sublingual or subcutaneous immunotherapy for allergic rhinitis?. Journal of Allergy and Clinical Immunology , 137 (2), 339-349.
Scadding, G. W., Calderon, M. A., Shamji, M. H., Eifan, A. O., Penagos, M., Dumitru, F., ... & Plough, A. G. (2017). Effect of 2 years of treatment with sublingual grass pollen immunotherapy on nasal response to allergen challenge at 3 years among patients with moderate to severe seasonal allergic rhinitis: the GRASS randomized clinical trial. Jama , 317 (6), 615-625.
Seidman, M. D., Gurgel, R. K., Lin, S. Y., Schwartz, S. R., Baroody, F. M., Bonner, J. R., ... & Ishman, S. L. (2015). Clinical practice guideline: allergic rhinitis. Otolaryngology–Head and Neck Surgery , 152 (1_suppl), S1-S43.
Small, P., Keith, P. K., & Kim, H. (2018). Allergic rhinitis. Allergy, Asthma & Clinical Immunology , 14 (2), 51.
Wallace, D. V., Dykewicz, M. S., Oppenheimer, J., Portnoy, J. M., & Lang, D. M. (2017). Pharmacologic treatment of seasonal allergic rhinitis: synopsis of guidance from the 2017 Joint Task Force on Practice Parameters. Annals of internal medicine , 167 (12), 876-881.
Wheatley, L. M., & Togias, A. (2015). Allergic rhinitis. New England Journal of Medicine , 372 (5), 456-463.
