Maternal and fetal immune responses to human trophoblast antigens.

Maternal and fetal cord leukocytes were tested in cytotoxicity assays against cultured autochthonous trophoblast cells. Significant lysis occurred with both categories of leukocyte, but the degree of cytotoxicity was less with fetal cells. These results suggest reduced fetal immunocompetence, the presence of fetal suppressor cells, or the presence of histocompatibility factors in trophoblast. Both fetal and maternal sera exhibited blocking activity in these tests and the source of this activity is discussed. The presence of particulate placental antigen inhibited trophoblast lysis by maternal leukocytes and no difference was observed between the effects of autochthonous and heterologous antigens.