Immune responses during pregnancy. Evidence of suppressor cells for splenic antibody response.

Abstract

The primary Ig[immunoglobulin]M antibody response to sheep erythrocytes in vivo and in vitro was markedly decreased in spleen cells of pregnant mice, compared to age-matched female controls. Decreased antibody synthesis appeared to be mediated by nonspecific suppressor cells, because addition of pregnant spleen cells to the normal spleen cell cultures caused significant suppression of plaque-forming-cell responses of the normal spleen cells. Suppressor cell activity was not observed in lymph nodes of pregnant mice. At least 2 populations of pregnant spleen cells exerted a suppressor cell activity; one was T [thymus-derived] lymphocytes and the other a nylon-adherent cell present in the B[bone marrow-derived]-cell-enriched macrophage-depleted fraction. Pregnant spleen cells cultured in vitro secreted a soluble suppressive factor(s) into the supernatant medium.