Increased levels of interleukin-6 in seminal plasma of infertile men.

The presence of various cytokines, namely the tumor necrosis factor (TNF-alpha), interferon (IFN-gamma), and interleukins (IL-1 beta and IL-6), was investigated in seminal plasma of fertile, infertile, and immunoinfertile men using specific immunoradiometric assays. TNF-alpha and IL-1 beta were not detected. IFN-gamma was detected, but the differences between the levels of fertile and infertile/immunoinfertile were not significant (P > 0.05). IL-6 was detected in seminal plasma with significantly higher levels in infertile/immunoinfertile men compared to those of fertile men. IL-6 was also present in sera, and interestingly, the levels in sera were lower than those in seminal plasma. IL-6 levels in seminal plasma correlated significantly with some sperm parameters and penetration rates in the human sperm penetration assay (SPA). These findings suggest that IL-6 is associated with infertility and may be of importance in specific diagnosis and treatment of male infertility.