Inhibition of mitogen and allogeneic stimulated lymphocyte growth by human amniotic fluid: lack of correlation between alpha-fetoprotein level and in vitro immunosuppression.

The influence of human amniotic fluid from women at 16-18 wk gestation on the in vitro proliferation of human peripheral lymphocytes stimulated with various mitogens (PHA, Con A and PWM) and with allogeneic cells in the one- and two-way mixed lymphocyte reaction (MLR) was studied. It was seen that amniotic fluid inhibits nonspecifically the responsiveness of the various subpopulations of cells induced to proliferate. It was also demonstrated that the suppression depends on the concentration of the immunosuppressive agent(s), since diluted amniotic fluids showed less inhibitory capacity. In order to detect a possible immune action for alpha-fetoprotein (AFP), the levels of the protein in the amniotic fluid supplemented cultures were correlated with the inhibitory properties of the fluids. No correlation was encountered, indicating that AFP is not mainly responsible for the in vitro immunosuppressive properties of human amniotic fluid on the in vitro test of cell-mediated immunity here utilized.