The use of serum-free medium delays, but does not prevent, the cytotoxic effects of seminal plasma in lymphocyte cultures: implications for studies on HIV infection.

Evidence indicates that seminal plasma is cytotoxic when used in lymphocyte cultures. In fact, an amine oxidase which is normally present in Fetal Calf Serum (FCS) causes spermine oxidation and, finally, cytotoxic substances are released. This seminal quality might obviously hamper studies aiming to evaluate the role of semen in HIV sexual transmission, since lymphocytes are generally used as target or effector cells in virological or immunological studies on HIV. We evaluated the efficacy of FCS free-medium, heat inactivated seminal plasma and/or the washing-out of cultures after a three hour incubation period in preventing the cytotoxicity to lymphocytes. Results show that when cultures are carried out in the absence of FCS and/or after seminal plasma removal, cytotoxicity is not prevented, although delayed. This finding indicates that, along with still unrecognized additional factors, spermine oxidation is still an important factor for semen cytotoxicity, and this considerably hampers any immunological and virological study, requiring the use of lymphocytes, concerning seminal fluid.