Role of spermine in the cytotoxic effects of seminal plasma.

This report further characterizes the cytotoxic properties of seminal plasma and provides evidence for a role of spermine oxidation in the generation of seminal plasma cytotoxicity. Addition of spermine to lymphocyte cultures was found to result in a cytotoxic effect similar to that observed upon addition of seminal plasma. Furthermore, although seminal plasma is not cytotoxic in serum-free medium, addition of monoamine oxidase was sufficient to result in the generation of seminal plasma-associated cytotoxicity. Analysis of 73 individual seminal plasma samples indicated that all were cytotoxic, suggesting that this is an intrinsic property of seminal plasma. These results support a mechanism for seminal plasma cytotoxicity in which oxidation of spermine in seminal plasma by the amine oxidase of fetal calf serum results in generation of a cytotoxic product. It is hypothesized that this product plays a significant role in the phenomenon of seminal plasma immunosuppression. The general application of this principle to other fluids and tissues is discussed.