Increased IL-18 levels in seminal plasma of infertile men with genital tract infections

PROBLEM: Interleukin (IL)-18 is a novel cytokine, previously known as interferon (IFN)-gamma inducing factor. We evaluated the levels of IL-18 and IFN-gamma in seminal plasma (SP) of fertile and infertile men. METHOD OF STUDY: Semen samples were obtained by masturbation from 80 men, and were examined for the levels of IL-18 and IFN-gamma by enzyme-linked immunosorbent assay. Seven groups were included: (i) fertile men (n = 18), (i) infertile men with genital tract infections (n = 17), (iii) with varicocele (n = 15), (iv) with Klinefelter syndrome (n = 6), (v) with cryptorchidism (n = 7), (vi) with mumps orchitis (n = 7), and (vii) with idiopathic testicular lesions (n = 10). RESULTS: Mean levels of IL-18 were higher in SP from infertile men with genital tract infections compared with SP from other groups except Klinefelter syndrome (P < 0.05). However, no significant differences could be detected for IFN-gamma. A significant positive correlations was found between IL-18 and IFN-gamma in total patient population (P < 0.001). Moreover, a negative correlation was observed between IL-18 and sperm concentrations, and motility (P < 0.01 and < 0.03, respectively). Furthermore, there was a positive and statistically significant association between IL-18 and IFN-gamma levels in SP of infertile men with genital tract infections (P < 0.0001). However, there was no relationship between IL-18 and IFN-gamma, and semen parameters in the same group. CONCLUSION: SP IL-18 levels were increased in men with urogenital infections. Thus, the elevated expression of IL-18 in SP may be used as a diagnostic marker in the male genital tract infections.