Maternal alloantibody responses during early pregnancy detected by a cellular enzyme-linked immunospecific assay.

Using a cellular enzyme-linked immunospecific assay (CELISA), we have examined sera from nulliparous women and women in the first trimester of a first or subsequent pregnancy for the presence of antibodies directed to surface determinants on peripheral blood lymphocytes from unrelated donors. Maternal antibody activity was found in sera from 1/13 nulliparae, 19/37 primigravidae, and 8/12 multigravidae. Cytotoxic antibody activity was present in 3/12 multigravidae but in no other group. Absorption with packed, pooled platelets did not remove the antibody activity from three of the primigravid sera; unabsorbed sera, however, bound equally well to T and B lymphocytes. These data suggest that the antibody detected by CELISA is not directed to any of the classical HLA antigen series (-A, -B, -C, or -DR) but may be directed to the HLA linked non-class I HT antigen system.