Maternal cell-mediated immunity in pregnancy--lymphocyte responses of mothers and their non-pregnant HLA identical sisters to paternal HLA.

The mixed lymphocyte reactions (MLR) of normal pregnant women and their non-pregnant HLA identical sisters have been compared, using paternal and unrelated lymphocytes as stimulator cells. Primary and secondary responses were differentiated by studying 7 day MLR time courses. All responses were of a primary nature, with neither stimulation nor suppression of the maternal MLR. These data clearly demonstrate the absence of maternal cellular sensitization to fetal (paternal) HLA.