[Studies of immunosuppressive substances in human seminal plasma]

Endogenous opioids, which have been shown to exhibit pharmacological and physiological activity on the immune system, have recently been reported to inhibit rosette formation between human T lymphocytes and sheep red blood cells. Because those opioids were found at a higher concentration in seminal plasma than in plasma, we studied whether seminal plasma could influence E rosette formation in 23 patients who complained of infertility. Seminal plasma significantly inhibited E rosette formation. With the dilution of seminal plasma, the percentage of E rosette formation increased. The incubation mixture of naloxone prevented the inhibition of E rosette formation produced by seminal plasma. The percentage of E rosette formation was significantly inhibited in azoospermia and oligozoospermia than in normozoospermia. In conclusion, these results suggest that opioids exert a suppressive effect on E rosette formation and may play a role in human spermatogenesis.