Immunity: Your Body's Defense against Infection, BUT what is it?
- Emma Werling
- May 27, 2022
- 2 min read
Immunity is the ways in which your body defends itself against infections such as the case with bacteria, viruses, fungi and parasites.
Forms of Immunity and Adaptive Response
The body first takes protection from infection and disease through the innate immune system including phagocytes, leukocytes, and natural killer cells (U.S. National Library of Medicine, 2020). If this first line of defense fails, then the adaptive immune system takes over, which is where T cells, B cells and antibodies come into play (U.S. National Library of Medicine, 2020). Further explanation of this is that when an antigen begins to circulate the body may destroy the antigen known as T-cell function or cellular immunity or the body may create antibodies known as B-cell function or humoral immunity (Dlugasch & Story, 2021).
While the T and B cells are produced by the body naturally, there are other ways for people to help the body’s defenses. This can be seen with active immunity in the case of vaccinations. Also seen with passive immunity, which was the case when people who had Covid donated serum from their blood that contained antibodies. These antibodies could then be administered to people to help develop passive immunity, even if temporary.
Digging Deeper: Active vs. Passive Immunity
Active immunity deals with exposure to an antigen through vaccination or invasion, then the body makes antibodies (Dlugasch & Story, 2021). The person is then protected long-term, such as the case with chickenpox (Dlugasch & Story, 2021).
Passive immunity deals with exposure to antibodies, such as when a person is exposed to these antibodies made “by another person, animal or recombinant DNA” (Dlugasch & Story, 2021). However, because the person is not actually producing their own antibodies, the immunity is short-lived, which can be seen in the case of breastfeeding and how infants obtain antibodies from their mothers (Dlugasch & Story, 2021).
Autoimmune Disorders: Altered Immune Response
There are three categories of altered immune response including exaggeration (hypersensitivity), failure of self-recognition (autoimmunity), or diminution (immunodeficiency) (Dlugasch & Story, 2021).
More specifically, SLE and rheumatoid arthritis are type III immune complex hypersensitivity reactions that originate with B cells (Dlugasch & Story, 2021). Whereas Crohn disease is type IV reaction that originates with T cells (Dlugasch & Story, 2021). These autoimmune diseases occur because the body cannot differentiate self-antigens from nonself foreign antigens (Dlugasch & Story, 2021). Something that may contribute to autoimmune disease includes molecular mimicry in which “exogenous trigger may cause autoimmunity when the antigen (e.g., pathogen) looks like an antigen already present” (Dlugasch & Story, 2021).
References
Dlugasch, L., & Story, L. (2021). Applied Pathophysiology for the advanced practice nurse.
Jones & Bartlett Learning.
U.S. National Library of Medicine. (2020). The innate and adaptive immune systems.
InformedHealth.org [Internet]. Retrieved January 10, 2022, from
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