The actions of composite trophoblast antigens in microvillus preparations upon cultured maternal lymphocytes from early first pregnancies.

The effect of placental microvillus preparations (MVP) on lymphocytes in whole blood cultures obtained from mothers in the early stages of their first pregnancies was studied. Variable dilutions and variable harvesting were used to construct kinetic curves of [6-3H]-thymidine uptake per day. Significant responses (P less than 0.02 to 0.05) were observed in autologous plasma and heterologous serum with and without phytohemagglutinin. The responses showed a variability which may be explained by chance combination of similar MVP and in vivo trophoblast antigens, some with stimulatory and others with suppressor actions. The presence of a blocking antibody to a suppressor antigen in autologous plasma could also contribute.