Inhibitory receptors sensing HLA-GI moleciiles in pregnancy: Decidua-associated natural killer cells express LIR-1 and CD94/NKGZA and acquire p49, an RLA-GI-specific receptor

摘要

Trophoblastic cells lack classical HLA class I and class 11 molecules but express HLA-GI. Although this may prevent allorecognition by maternal T cells, it renders trophoblastic cells potentially susceptible to lysis hy natural killer (NK) cells. As shown here, only a fraction of peripheral blood NK cells in pregnant women express the HLA-GI. specific CD94/NKGZA and/or LIR-1 receptors. However, all NK cells isolated from maternal decidua during the first trimester expressed either one or both of these receptors. Perhaps more importantly, a fraction of cells expressed p49, an HLA-GI-specific inhihitory receptor, undetectable in peripheral-blood NK cells. p49 was expressed on virtually all NK cells isolated from placenta at term. Functional analyses revealed that the HLA class I-negative 221 Iymphoblastoid cell line transfected with HLA-GI was only partially protected from lysis by peripheral-blood NK cells isolated from pregnant women, whereas it was fully protected from decidual NK cells. As indicated by the addition of specific antibodies to cytolytic tests, all the above receptors contributed to HLA-GI recognition by decidual NK cells, althongh p49 would appear to play a Predominant role.