IS THE EXPRESSION OF CLASSICAL HLA CLASS-I ANTIGENS ON TROPHOBLAST OFIMPORTANCE FOR HUMAN-PREGNANCY

PROBLEM: Human leukocyte antigen (HLA)-C and possibly also HLA-B seem to be expressed on the extravillous trophoblast. These antigens carry epitopes that function as ligands for natural killer (NK)-cell-inhibit ory receptors. Antitrophoblast cytotoxicity mediated by decidual Mt ce lls might be involved in miscarriage. We thus found it relevant to elu cidate whether parental HLA-C and -Bw polymorphism play a role in recu rrent miscarriage (RM). METHOD OF STUDY: HLA-C and -Bw investigations by DNA-based techniques were undertaken in 35 couples with unexplained RM and in 30 couples with normal fecundity. The number of HLA-C- and -Bw-related supertypic specificities that can bind NK-cell-inhibitory receptors was evaluated in selected couples. RESULTS: The proportions of couples with RM and control couples carrying four HLA-C alleles wit h the same NK-cell-inhibitory supertypic specificities were equal. In 46% of studied couples with RM, all four HLA-B alleles carried the HLA -Bw6 supertypic specificity, which was significantly higher than the c orresponding frequency (17%) in the control couples (P < 0.02). CONCLU SIONS: The expression of polymorphic HLA-C on trophoblasts does not se em to play a role in RM. Assuming that HLA-B is expressed on trophobla sts, we may suggest that the revealed predominance of HLA-Bw6 expressi on (which excludes the presence of HLA-Bw4-protective antigens) may pr edispose a particular couple to the RM phenomenon.