Is the expression of classical HLA class I antigens on trophoblast of importance for human pregnancy?
OBJECTIVE
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-inhibitory receptors. Antitrophoblast cytotoxicity mediated by decidual NK cells might be involved in miscarriage. We thus found it relevant to elucidate whether parental HLA-C and -Bw polymorphism play a role in recurrent miscarriage (RM).


METHODS
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 with 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 corresponding frequency (17%) in the control couples (P < 0.02).


CONCLUSIONS
The expression of polymorphic HLA-C on trophoblasts does not seem to play a role in RM. Assuming that HLA-B is expressed on trophoblasts, we may suggest that the revealed predominance of HLA-Bw6 expression (which excludes the presence of HLA-Bw4-protective antigens) may predispose a particular couple to the RM phenomenon.
Department of Clinical Immunology, Aalborg Hospital, Denmark.
O B
OB
Christiansen
H P
HP
Mohapeloa
B
B
Pedersen
A
A
Rosgaard
D000026:Abortion, Habitual / Q000276:immunology / Q000378:metabolism*; D000328:Adult; D000483:Alleles; D005260:Female; D015235:HLA-B Antigens / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D015236:HLA-C Antigens / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology / Q000378:metabolism; D008297:Male; D011247:Pregnancy / Q000276:immunology / Q000378:metabolism*; D014327:Trophoblasts / Q000276:immunology / Q000378:metabolism*
D015235:HLA-B Antigens; D015236:HLA-C Antigens