HLA-G and NK receptor are expressed in psoriatic skin - A possible pathwayfor regulating infiltrating T cells?

Recent data have suggested that in psoriasis, the T-infiltrating cells coul d be submitted to regulatory pathways, possibly through natural killer rece ptors. HLA-G binds to different natural killer receptors and is able to inh ibit T-cell functions, because this molecule is Induced by interferon-gamma , a major cytokine in psoriasis, we asked whether HLA-G and its receptor mi ght be expressed in this disease. Specific RNAs for HLA-G1 and HLA-G5 were consistently found in lesional skin specimens, soluble HLA-G5 transcripts b eing found only in psoriasis. HLA-G protein was found in all psoriatic sect ions, but never In normal skin controls. Double labeling demonstrated that HLA-G-positive cells were CD68(+), CD11c(+) macrophages. The NKR ILT2 was a lso present In psoriatic skin, the T CD4(+)-infiltrating cells expressing i ndeed ILT2, The demonstration of HLA-G and ILT2 expression in psoriatic ski n suggests that this pathway may act as an inhibitory feed back aimed to do wn-regulate the deleterious effects of T-cell infiltrate in this disease.