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Madeline Group 6: Define hypersensitivity and its relationship to allergy, autoimmunity, and allo immunity.
Hypersensitivity is an immune response to an antigen, which can be abnormal or over exaggerated in it’s presentation (Vitte et al., 2022). This response can sometimes lead to tissue damage, instead of a more normal response of immunity. Regardless, hypersensitivity is an important concept in understanding allergies, autoimmunity, and alloimmunity, all of which represent a different side of the immune system.
Allergy is a type of hypersensitivity where the immune system has an exaggerated response to an otherwise harmless antigen or allergen in a person’s environment (Özcan & Boyman, 2022). In the journal article by Vitte et al. (2022), an allergy reaction involves IgE antibodies and mast cells as the main components that lead to a host of symptoms from itching to critical anaphylaxis.
Autoimmunity is very distinct from allergies because it involves the immune system mistakingly recognizing the body’s own tissue and attacking it (McCance et al., 2023). Normally, the immune system can distinguish between self and non-self antigens (McCance et al., 2023). However, in the case of autoimmune disorders, a misdirected immune response becomes a hypersensitivity to oneself where defense mechanisms harm its own cells (McCance et al., 2023).
Alloimmunity is another form of hypersensitivity where the immune system reacts to antigens of the same species (Özcan & Boyman, 2022). For example, alloimmunity can be seen in blood transfusion reactions or organ transplant rejection (McCance et al., 2023). Although similar to autoimmunity, alloimmunity involves the reaction to foreign tissue rather one’s own tissue (McCance et al., 2023).
Özcan and Boyman (2022) expand on previous research that neutrophils may have a bigger impact on all three of these immune response than previously thought. These white blood cells are known to be present in hypersensitivity reactions and when fighting infection (McCance et al., 2023). However, they also play a vital role in the pathogenic processes of autoimmune disorders and alloimmunity issues like host versus graft disease (Özcan & Boyman, 2022). It’s only now that scientists are paying closer attention on how to treat such diseases by specifically targeting neutrophils (Özcan & Boyman, 2022). Since allergies, autoimunity, and alloimmunity have overlapping immune mechanisms, it makes sense to study these together.
References
McCance, K.L., Huether, S.E., Brashers, V.L., Rogers, J.L. (2023). Pathophysiology: The biological basis for disease in adults and children. (9th ed.) Maryland Heights, MO.: Mosby Elsevier.
Özcan, A., & Boyman, O. (2022). Mechanisms regulating neutrophil responses in immunity, allergy, and autoimmunity. Allergy, 77(12), 3567-3583. https://doi.org/10.1111/all.15505
Vitte, J., Vibhushan, S., Bratti, M., Montero-Hernandez, J. E., & Blank, U. (2022). Allergy, Anaphylaxis, and Nonallergic Hypersensitivity: IgE, Mast Cells, and Beyond. Medical Principles and Practice, 31(6), 501-515. https://doi.org/10.1159/000527481
Jieun Group 3. Describe the role of antigens in guarding against infection and T lymphocytes in destroying compromised cells.
Antigens are small molecules that serve as targets for antibodies and lymphocytes (McCance et al., 2023). An antigen refers to any foreign material, such as infectious agents, allergens, chemical agents, viruses, proteins, or bacteria, that triggers an immune response within the body. The role of antigens in guarding the immune system is to produce antibodies and activate immune cells like T cells and B cells. These antibodies bind to the antigen, destroying and eliminating its harmful effects. When antigens are detected by the immune system, an adaptive immune response is initiated, producing protective lymphocytes and antibodies.
Adaptive immunity, more specific than the innate immune system, provides lasting protection against pathogens. T lymphocytes carry out adaptive immune responses. Once a population of T cells has been created to combat pathogens, memory T cells will provide lifelong immunity against the pathogen (DeMaio et al., 2022). Cytotoxic T cells are responsible for destroying compromised and abnormal cells. When activated, these cells recognize specific antigens and release cytotoxic granules containing perforin, which creates pores in the compromised cell’s membrane, and granzymes, which induce apoptosis, a programmed cell death. (McCance et al., 2023, p. 249).
References
DeMaio, A., Mehrotra, S., Sambamurti, K., et al. (2022). The role of the adaptive immune system and T cell dysfunction in neurodegenerative diseases. Journal of Neuroinflammation, 19(1), 251. https://doi.org/10.1186/s12974-022-02605-9
McCance, K.L., Huether, S.E., Brashers, V.L., Rogers J.L. (2023). Pathophysiology: The biologicalhe basis for disease in adults and children. (9th ed.). Maryland Heights, MO.: Mosby Elsevie
