Soluble HLA-G in human placentas: synthesis in trophoblasts and interferon-gamma-activated macrophages but not placental fibroblasts.
The HLA class Ib antigen, HLA-G, is highly expressed in early gestation placentas where it is believed to modulate maternal-fetal immunological interactions. In this study, soluble isoforms (sHLA-G) encoded by intron 4-retaining transcripts were identified in first trimester placentas by immunohistochemistry using a mAb specific for the C-terminus of sHLA-G. Immunoreactive sHLA-G protein was localized to trophoblast cells and to villous mesenchymal cells with the morphological features of macrophages. Reverse transcriptase polymerase chain reaction analysis which used primers specific for intron 4 and the 3' untranslated region of the HLA-G gene showed that transcripts encoding sHLA-G were present in the trophoblast-derived Jeg-3 cells as well as interferon-gamma-activated myelomonocytic U937 cells but were absent and uninducible in placental fibroblasts. These results indicate that placental sHLA-G is synthesized in trophoblast cells and activated placental macrophages and support the postulate that placenta-derived sHLA-G modulates maternal and fetal immune cell functions during pregnancy.
Chu
W
W
Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City 66160-7400, USA.
Fant
M E
ME
Geraghty
D E
DE
Hunt
J S
JS
D000595:Amino Acid Sequence; D002460:Cell Line; D005260:Female; D005347:Fibroblasts / Q000276:immunology / Q000378:metabolism*; D006680:HLA Antigens / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D006801:Humans; D007150:Immunohistochemistry; D007371:Interferon-gamma / Q000494:pharmacology*; D008262:Macrophage Activation; D008264:Macrophages / Q000276:immunology / Q000378:metabolism*; D008969:Molecular Sequence Data; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D012333:RNA, Messenger / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012995:Solubility; D014327:Trophoblasts / Q000166:cytology / Q000276:immunology / Q000378:metabolism*
D006680:HLA Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I; D011257:Pregnancy Proteins; D012333:RNA, Messenger; D007371:Interferon-gamma