Seminal plasma modulates lymphokine-activated killer cell activity in vitro

We have previously reported that seminal plasma (SP) pool from donors and azoospermic patients can inhibit the NK response in vitro. In this study we investigated whether SP also inhibits the interleukin -2-activated natural cytotoxicity (LAK). Pools of SP from 10 healthy donors and 17 azoospermic patients were used. They were sterilized by filtration and stored at -20 degrees C until use. Anti-sperm antibodies were negative in all samples. Peripheral blood lymphocytes (PBL) obtained from volunteer donors were incubated during 16 hours in culture medium, RPMI alone, with 10% fetal calf serum (FCS) or with 10% human serum (HuS). The NK and LAK cytotoxicity assay was performed using the cell line K 562 labeled with 51Cr. In view of our results, we conclude that LAK activity is inhibited by SP when PBL are incubated in the absence of FCS. This inhibitory effect of SP is unrelated to cellular death and there is no difference between healthy and azoospermic seminal plasma.