HLA-G suppresses proliferation of CD4(+) T-lymphocytes.
HLA-G is a non-classical MHC class 1 molecule, expressed primarily on human foetal trophoblast cells, which exhibits almost no genetic polymorphism. Because of these unusual features, HLA-G has been suggested to help prevent maternal immune attack of the semi-allogeneic foetus. The aim of these experiments was to investigate the effects of HLA-G on T-lymphocyte responses by using MHC class II-bearing HLA-G transfectants as stimulators of a mixed lymphocyte reaction. The presence of HLA-G, but not classical HLA class I, on the surface of stimulator cells markedly suppressed thymidine incorporation by peripheral blood mononuclear responder cells from a class I-similar, class II-dissimilar male. The suppressive effect of HLA-G on the mixed lymphocyte reaction persisted after depletion of phagocytes and CD8(+) T-cells from the responder population, but the mixed lymphocyte reaction was entirely abolished by depletion of CD4(+) T-cells. These results suggest that HLA-G exerts a direct suppressive effect on CD4(+) T-lymphocytes, even in the absence of the CD8(+) cells with which other human MHC class I molecules are thought to interact. Thus, HLA-G may allow the foetus to escape maternal immune attack by modulating CD4(+) T-cell activity.
Bainbridge
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Reproduction and Development Group, Royal Veterinary College, Boltons Park, Hawkshead Road, EN6 1NB, Potters Bar, UK. dbainbridge@rvc.ac.uk
Ellis
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SA
Sargent
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D016516:CD4-CD8 Ratio; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology* / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes; D002455:Cell Division; D002460:Cell Line; D006680:HLA Antigens / Q000502:physiology*; D015789:HLA-A2 Antigen / Q000378:metabolism; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I / Q000502:physiology*; D006801:Humans; D013936:Thymidine / Q000378:metabolism
D006680:HLA Antigens; D015789:HLA-A2 Antigen; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I; D013936:Thymidine