High levels of soluble p55-TNF receptors in seminal and prostatic fluids of normal and infertile men

Purpose: To study the role of tumor necrosis factor (TNF) in the male reproductive system by examining the occurrence, source, and possible functional significance of soluble TNF receptors in seminal fluids of normal and infertile men. Materials and Methods: Concentrations of soluble TNF receptors (p55-sTNF-R and p75-sTNF-R) were measured by ELISA in human sera, seminal fluids, prostatic fluid and fluid obtained from an epididymal spermatocele. Results: The level of p55-sTNF-R in seminal fluids of normospermic men was ≃20-fold higher than in normal serum (13.9 ± 6.9 ng./ml. versus 0.7 ± 0.2 ng./ml.). In contrast, p75-sTNF-R, which occurs in serum at amounts higher than p55-sTNF-R, was almost indiscernible in the seminal fluids (<0.18 ± 0.28 ng./ml. versus 1.9 ± 0.6 ng./ml. in sera). Concentrations of p55-sTNF-R in seminal fluids of oligoasthenospermic and azoospermic men were similar to those of normospermic men (15.6 ± 8.5 ng./ml. and 14.9 ± 6.5 ng./ml., respectively). Higher p55-sTNF-R concentrations were found in prostatic fluids and first split ejaculates (39.8 ± 1.2 ng./ml. and 32 ± 1.7 ng./ml., respectively), while second split ejaculates and the fluid from an epididymal spermatocele were found to contain p55-sTNF-R at lower levels (10.8 ± 1 ng./ml. and 1 ng./ml., respectively). Conclusions: These findings suggest intense local biosynthesis of p55-sTNF-R in the prostate occurring independently of spermatogenesis. Possible functional implications are: 1) shielding of spermatozoa from the inhibitory effect of TNF in the female reproductive tract; 2) a role for TNF in the normal physiology of the prostate; and 3) blocking TNF-mediated immune response in the prostate, which may have beatings on the development of prostatic hypertrophy or cancer.