The human immune system is responsive to sex hormones. This results in functional differences in immunity between the sexes.Women tend to have a more active immune system compared to men, and are slightly more resistant to bacterial infection and other types of infection. The female immune system is also more prone to developing autoimmune diseases, which may be linked to its higher level of activity. The day-to-day activity of the immune system can also fluctuate throughout the menstrual cycle, further demonstrating the strong influence of sex steroids. The slightly weaker resistance to infection of men appears to be caused by testosterone, which is an immunosuppressive hormone. Androgens may modulate the immune system directly, through their conversion to estrogens, or by modifying glucocorticoid activity.
Anabolic/androgenic steroids have displayed both immunostimulatory and immunosuppressive actions in animal models. Given that these drugs can influence the immune system through a variety of pathways, and anabolic steroids are a fairly diverse class of drugs, their effects on the immune system may vary depending on the particular conditions. When used therapeutically, changes in immune system functioning are usually minor, and have not amounted to strong immunostimulation or immunosuppression. Anabolic/androgenic steroids have also been used safely in many immunocompromised patients, such as those with muscle wasting associated with HIV infection, without any significant change in immune system or viral markers.
The use of anabolic/androgenic steroids in supratherapeutic doses may slightly impair immune system functioning, reducing an individual’s resistance to certain types of infection. In one study, steroid abusers were shown to have lower serum levels of IgG, IgM, and IgA immunoglobulins (antibodies) compared to bodybuilding controls, consistent with immunosuppression. Although this may logically increase the chance of contracting certain types of illness, a significant increase in the history of illness could not be established in these same steroid abusers. Given the very random nature of illness, however, it may be difficult to establish such a link without extensive study. The effect of hormone manipulation on immunity should also be temporary, and return to a normal state once pre-treated hormonal chemistry is restored. Individuals remain warned of the potential for minor immunosuppression and increased chance of illness with steroid abuse.
Wlliam Llewellyn (2011) - Anabolics