Evidence for the expression of HLAA-C class I mRNA and protein by human first trimester trophoblast.
In this study, evidence is provided that normal human first trimester extravillous trophoblast expresses class I HLA-C molecules in addition to HLA-G. cDNA from highly purified trophoblast cells obtained by flow cytometric sorting was amplified by reverse-transcriptase PCR using HLA locus-specific primers. The identity of the product was confirmed by Southern blotting and hybridization by a second HLA-C-specific oligonucleotide. HLA-C mRNA was clearly demonstrated in all trophoblast samples as well as in JEG-3 and BeWo choriocarcinoma cells. JAR choriocarcinoma cells did not express HLA-C. The presence of HLA-C protein in extravillous trophoblast was investigated using a panel of Abs: L31 is specific for heavy chains of all HLA-C alleles; Q1/28 reacts with all HLA class I products except HLA-G; HC-10 has preferential reactivity with HLA-B and HLA-C heavy chains. We performed 35S metabolic and 125I surface labeling of normal first trimester trophoblast and found abundant HLA-C intracellularly together with low levels of expression of both the beta 2m-associated forms and free heavy chains on the surface. Flow cytometric analysis of normal trophoblast confirmed the expression of a class I HLA molecule distinct from HLA-G by positive reactivity with Q1/28. Immunohistologic studies of first trimester placenta and the implantation site clearly showed expression of HLA-C in all extravillous trophoblast populations. Our results demonstrate the presence of two HLA class I molecules, HLA-G and HLA-C, on the surface of extravillous trophoblast. These results have implications in understanding how maternal uterine lymphocytes, notably the abundant NK-like cells, might recognize the implanting placenta.
King
A
A
Research Group in Human Reproductive Immunobiology, Department of Pathology, University of Cambridge, United Kingdom.
Boocock
C
C
Sharkey
A M
AM
Gardner
L
L
Beretta
A
A
Siccardi
A G
AG
Loke
Y W
YW
D001483:Base Sequence; D005260:Female; D005434:Flow Cytometry; D015236:HLA-C Antigens / Q000096:biosynthesis / Q000235:genetics*; D006801:Humans; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011233:Precipitin Tests; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000096:biosynthesis / Q000235:genetics*; D011261:Pregnancy Trimester, First / Q000235:genetics / Q000276:immunology; D012333:RNA, Messenger / Q000096:biosynthesis*; D014327:Trophoblasts / Q000378:metabolism*
D015236:HLA-C Antigens; D011257:Pregnancy Proteins; D012333:RNA, Messenger