Influence of histocompatibility antigens in recurrent spontaneous abortion couples and on their reproductive...

To determine if human leukocyte antigens (HLA) play any role in the aetiology of recurrent spontaneous abortion (RSA), a substantial group of RSA couples were studied, and their reproductive performances in a 3-year follow-up recorded.

HLA typing was performed for HLA-A, -B, and DR antigens in both partners of 75 couples with unexplained RSA, and compared with a control group of 30 fertile couples that never experienced abortion. A further 57 couples of this group were studied for their reproductive performance in a 3-year follow-up, and subdivided into three subgroups: 1) couples that achieved successful pregnancy during the follow-up, and subdivided into three subgroups: 1) couples that achieved successful pregnancy during the follow-up; 2) couples that experienced abortion and no livebirth during the follow-up; and 3) couples that experienced infertility during the follow-up.

There were no significant differences for antigen frequency in all the different HLA loci, and HLA antigen sharing between all the RSA couples and controls. Significant increase of sharing for HLA-DR locus was observed in the couples that aborted during the follow-up with respect to the couples that achieved livebirth and controls (P < 0.03 and P < 0.02 respectively), and significantly increased frequency of B44, DR5 antigen combination in the same comparison (P < 0.03). No significant differences were observed in terms of the interval between conceptions in couples without antigen sharing with respect to couples with 1, 2 or more antigens shared, and antigen sharing in Locus A, B or DR.

The results suggest that gene(s) disadvantageous for reproduction may exist between the HLA-B and -DR chromosomal region which influences the pregnancy outcome in RSA couples, and that HLA-antigen sharing itself does not influence the outcome.