Gonadal steroids and salivary IgA in healthy young women and men.

Empirical evidence from clinical, nonhuman animal, and in vitro studies point to links between immune function and gonadal steroids, including potential androgenic immunosuppression and estrogenic immunoenhancement. This study was designed to test links between steroids and one marker of mucosal humoral immunity-immunoglobulin A (IgA) in healthy individuals, to facilitate comparisons with other species and clinical populations, as there are few existing studies with healthy humans that also allow gender/sex investigations. Participants (86 women, 91 men) provided a saliva sample for measurement of testosterone (T), estradiol (E(2)), and IgA. Results showed that E(2) was significantly and positively correlated with IgA in women, and group analyses by E(2) quartile showed that this association was linear. No significant correlations or nonlinear associations were seen between T and IgA in men or women, or E(2) and IgA in men. Evidence from this study indicates that IgA and E(2) are significantly associated in healthy premenopausal women.