Human pregnancy serum inhibits proliferation of T8-depleted cells and their interleukin-2 synthesis in mixed lymphocyte cultures.

T8-depleted and unfractionated T lymphocytes allogeneically stimulated and cultured in the presence of pregnancy sera exhibit an inhibition of cellular proliferation and interleukin-2 synthesis, respectively. Unfractionated T cells show a decrease in their cytotoxicity in the presence of these sera. The inhibition of cytotoxicity could be due to the deficit of IL-2 observed since if exogenous IL-2 is added to the cultures T4/LEU3a-depleted allogeneically stimulated cells reach the same degree of cytotoxicity whether cultured in normal human serum or pregnancy serum. A possible mechanism to explain the inhibition of mixed lymphocyte cultures by pregnancy serum could therefore be decrease of cellular proliferation of the T8-depleted subpopulation with a decrease in IL-2 synthesis, implying an inhibition of cytotoxic effector cells.