Testing androgen-induced immunosuppression: Environmental androgens as a model system for steroid-immune interaction

Area of Science:

• Comparative immunology
• Endocrinology
• Herpetology

Background:

• Hormonal regulation of physiology is extensive, yet specific relationships, like that between gonadal hormones and immunity, are debated.
• The hypothesis that androgens suppress immune function is prevalent but lacks consistent evidence.

Purpose of the Study:

• To test the hypothesis that androgens inhibit immunocompetence in the American alligator (Alligator mississippiensis).
• To investigate the effects of androgen exposure on both innate and acquired immune function in developing alligators.

Main Methods:

• Developing alligators were exposed to 17-α-methyltestosterone (MT), a non-aromatizable androgen, during early development.
• Immune function was assessed by quantifying leukocyte profiles, innate immunity (hemolysis-hemagglutination), and acquired immunity (antibody titers) after antigen exposure.

Main Results:

• No significant differences were observed in leukocyte ratios or proportions between androgen-exposed and control groups.
• Innate immune function showed no significant differences between groups.
• Androgen-exposed (masculinized) alligators exhibited significantly higher antibody titers, indicating enhanced acquired humoral immunity.

Conclusions:

• The findings reject the hypothesis that androgens suppress immunocompetence in American alligators.
• Androgens may enhance acquired humoral immune responses while having a neutral effect on innate humoral immunity in crocodilians.