Determinants of immunological responsiveness in recurrent spontaneous abortion.

A defined group of 20 women suffering recurrent spontaneous abortions of unknown etiology was studied for determinants relevant to immune responsiveness. A low prevalence of serum anti-CMV antibodies (35%; cf, 65% in controls)--but not anti-herpes-simplex-virus or Epstein-Barr virus antibodies--was noted. Only two (10%) of these women had lymphocytotoxic antibodies following their repeated pregnancies; low titer anti-sperm antibody was present in two other of these women. Whereas there was no significantly increased sharing of HLA-A or -B antigens within these couples compared with controls, there was an increased incidence of apparent HLA-B antigen homozygosity in the women. These data indicate a degree of immunological nonresponsiveness both to cytomegalovirus and to cell-surface alloantigens in habitually aborting women and, together with MLC data, provide further evidence that immunogenetic events may be relevant to reproductive success.