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Numerous studies have examined relationships between adrenal glucocorticoids and the immune system’s ability to fight disease. The relationship can vary, with glucocorticoids having either stimulatory or inhibitory effects. The pathogenic bacterium Mycoplasma gallisepticum (MG) elicits an adaptive immune response in birds, in which B cells produce MG-specific antibodies to fight the infection and prevent reoccurrence. Previous research found that Eastern Bluebirds that produce the most antibodies in response to MG infection also have the highest glucocorticoid levels. This finding led to the current study investigating whether corticosterone, the primary glucocorticoid in birds, stimulates production of antibodies in response to immune challenges, or if the nature and virulence of the challenge influences corticosterone production. I compared results from the current study wherein Eastern Bluebirds were administered corticosterone following vaccination against MG with those of the previous study where birds were infected with the live pathogen. In contrast to previous findings, I found no evidence of a positive relationship between corticosterone levels and MG-antibody production in vaccinated birds compared to controls. In addition, the strength of the humoral immune response was not altered in birds administered corticosterone. These findings suggest that the positive relationship between corticosterone and humoral immunity in previous work is associated with virulence of the pathogen.
Smith, Joshua, "The Relationship Between Glucocorticoids and the Humoral Immune Response to Mycoplasma gallisepticum Challenges in Eastern Bluebirds" (2020). Honors Theses. 1389.
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