Human semen induces interleukin 10 and 70 kDa heat shock protein gene transcription and inhibits interferon-gamma messenger RNA production in peripheral blood mononuclear cells.

The influence of semen on immunity in sexually active women has been scarcely studied. The effect of human semen on production of messenger RNA (mRNA) for the anti-inflammatory TH2-related cytokine, interleukin-10 (IL-10), the 70 kDa heat shock protein (HSP70) and the pro-inflammatory TH1-related cytokine, interferon-gamma (IFN-gamma) was examined. Co-incubation of peripheral blood mononuclear cells (PBMC) from 10 women with a non-cytotoxic 1:50 dilution of semen lead to induction of IL-10 mRNA. Semen from each of seven different men tested induced IL-10 mRNA in PBMC. IL-10 protein was also released into the culture supernatant after PBMC-semen co-culture. Similarly, semen induced transcription of the HSP70 gene in PBMC obtained from 10 women. In contrast, semen did not induce IFN-gamma mRNA in any of the female PBMC donors. Furthermore, semen markedly inhibited IFN-gamma mRNA production without affecting cell viability in PBMC that were cocultured with phytohaemagglutinin, a potent IFN-gamma-inducing T-cell mitogen. Thus, human semen is both an inducer of an anti-inflammatory (TH2) immune response and an inhibitor of pro-inflammatory (TH1) cell-mediated immunity.