The role of MHC class I expression in developmental tumours

Expression of HLA class I (-like) genes by two developmental tumour cell lines representing embryonic (Tera-2) and extra-embryonic (Jeg-3) origins is reviewed. The Tera-2 embryonal carcinoma cells are HLA negative but can be induced by gamma interferon to express HLA-A, -B, -C, and apparently -E and G genes. Jeg-3 choriocarcinoma cells constitutively express HLA-G and low levels of a novel HLA-C gene product. The NK sensitivity of the developmental tumour cell types has been assessed and the biochemical characteristics of the surface molecules expressed by the trophoblast derived cells has been further documented. The biological role of these novel HLA molecules in the context of the maternal acceptance of the fetal-semi-allograft is discussed.