Surface expression of HLA-C antigen by human extravillous trophoblast

In this paper definitive evidence that the classical class I product, HLA-C , is expressed on the surface of normal trophoblast cells is provided. HLA- C transcripts were sequenced from cDNA isolated from first trimester tropho blast cells obtained by flow cytometric sorting. Both paternal and maternal alleles were transcribed. HLA-C proteins were demonstrated by biochemical analysis and found on the cell surface in association with beta(2)-microglo bulin. Upregulation of cell surface HLA-C but. not HLA-G expression after i nterferon (IFN)-gamma treatment was demonstrated by flow cytometric analysi s. Immunohistology has confirmed HLA-C is expressed by all extravillous sub populations in vivo. The question of whether trophoblast HLA-C molecules in teract with decidual NK cells expressing killer Ig-like receptors (KIR) has also been addressed. Our results demonstrate that extravillous trophoblast expresses at least two HLA class I molecules, HLA-G and HLA-C on the cell surface. (C) 2000 Harcourt Publishers.