Sex steroids, pregnancy-associated hormones and immunity to parasitic infection.

A wealth of evidence has accumulated that illustrates the ability of sex-associated hormones to influence directly a variety of diverse immunological functions. Thus, it is not surprising that differences have also been noted between the sexes in their relative susceptibility to parasitic infections. Furthermore, during pregnancy, much of the observed maternal immunomodulation, essential for fetal survival, has been attributed to changes in the levels of steroid hormones. These pregnancy-induced alterations in immune function can also have profound effects on the course of parasitic infection. In this article, Craig Roberts, Abhay Satoskar and James Alexander review the immunological basis for differences in the relative susceptibilities of males, non-pregnant females and pregnant females to parasitic infection, particularly leislumaniasis and toxoplasmosis. They also discuss the role of the major sex- and pregnancy-associated hormones in mediating these effects.