Maternal alloimmunisation in pregnancy. In vitro studies of T cell-dependent immunity to paternal alloantigens.

A secondary in vitro allograft reaction was used to demonstrate that spleen cells derived from allogeneically mated inbred mice were immunised against paternal alloantigens. In addition to the heightened alloantigen-specific in vitro response of these spleen cells, it was also found that spleen cells froma a wide variety of syngeneically and allogeneically mated mice were nonspecifically more reactive in the in vitro allograft reaction than spleen cells from virgin mice. However, when spleen cells freshly harvested from allogeneically mated mice were tested in a direct 51Cr release assay, lysis of target cells bearing the paternal alloantigens was demonstrable in only one-third of the experiments. It is proposed that T cell immunisation to paternal alloantigens occurs in pregnancy, but that cell-mediated cytotoxicity is inhibited.