In the human body, there are many mechanisms of defense. Mechanisms that maintain homeostasis at large and actions that mainly protect the body at the cellular level. In the scenario presented, the 16-year-old boy is diagnosed with strep throat and prescribed the expected treatment course, amoxicillin 500 mg PO BID x10 days with 20 pills dispensed. When he took the first dose, he immediately complained of tongue swelling, lip swelling, and shortness of breath with wheezing. 911 was called, and his allergic reaction was emergently treated.
Physiologically, the response his body had to penicillin is called a hypersensitivity reaction. “Hypersensitivity reactions (HR) are immune responses that are exaggerated or inappropriate against an antigen or allergen” (Vaillant, 2021). In hypersensitivity with anaphylaxis, the reaction starts immediately after exposure to antigen/allergen. Noting the boy’s emergent symptoms started immediately after the ingestion of the penicillin. Penicillin is the most commonly reported medication allergy (Patterson, 2021).
Immediate hypersensitivity reactions (HR), including anaphylaxis, are mediated by IgG and IgM cells. The IgG binds to mast cells and basophils. When the mast cells and basophils contact the antigen, the IgE in the patient’s cell is activated. This activation causes degranulation of the host cell and ultimately releases histamines. Histamines cause “vascular leak, bronchoconstriction, inflammation, and intestinal hypermotility” (Vaillant, 2021). Enzymes involved in the process also cause inflammation.
When the body has a hypersensitive reaction, the inflammation process is activated, causing a systemic response by the immune system. In this case, after ingesting the penicillin, the patient’s tongue and lips started to swell, and the swelling in the lungs caused the presentation of the wheezing. Also, the activated IgE on basophils releases histamine causing the mast cells to release more histamine, causing vasodilation. In the lungs, the histamine causes cell destruction and fluid to leak into the alveoli. At the same time, vascular permeability is increased, causing fluid to leak from the vessels. This will all cause the reaction in the patient you see of swelling of the tongue, lips, and throat causing shortness of breath and wheezing, ultimately potentially obstructing his airway. (Rebar et al., 2019)
Genetics is the study of heredity, aka how parents pass on traits to their children. This includes the variation of a gene and the trait it controls called an allele (Rebar et al., 2019). The same way a person’s genetics can determine a blue versus green eye color, the body determines the immune response based on specific alleles, specifically the Human Leukocyte Antigen (HLA) allele (Drug allergies 2021). Meaning depending on the genetic makeup you got from your parents, your body may react a certain way when exposed to certain medications such as penicillin. The primary role of the HLA molecules is to regulate the immune response (Drug allergies 2021). HLA molecules are expressed on the surface of most cells with a nucleus and monocytes, macrophages, dendritic cells, and T lymphocytes. This means that these are the cells involved in the immune response responsible for hypersensitivity response, including anaphylaxis.
Gender in specific can make someone susceptible or not susceptible to particular processes or diseases. For example, a woman can be more susceptible to autoimmune diseases or when the immune system cannot decipher the difference between their healthy cells and potentially harmful antigens and therefore treats them the same (Angum et al., 2020). Some believe that the incidence is higher is hidden in the XX chromosome combinations because the X chromosome is more prominent in size and therefore may have 800-900 more genes (Angum et al., 2020). Being that the rules of genetics still apply, I do not think this would change my response.
References
Angum, F., Khan, T., Kaler, J., Siddiqui, L., & Hussain, A. (2020, May 13). The prevalence of autoimmune disorders in women: A narrative review. Cureus. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7292717/.
Drug allergies. WAO. (n.d.). https://www.worldallergy.org/education-and-programs/education/allergic-disease-resource-center/professionals/drug-allergies.
Patterson, R. A. (2021, July 21). Penicillin allergy. StatPearls [Internet]. https://www.ncbi.nlm.nih.gov/books/NBK459320/.
Rebar, C. R., Heimgartner, N. M., & Gersch, C. J. (2019). Pathophysiology made incredibly easy! Wolters Kluwer.
Vaillant, A. A. J. (2021, June 11). Immediate hypersensitivity reactions. StatPearls [Internet]. https://www.ncbi.nlm.nih.gov/books/NBK513315/.
