Human trophoblast cells in culture express an unusual major histocompatibility complex class I-like antigen

We present evidence that the trophoblast cells obtained from first trimester placentae by a culture method developed in our laboratory express a class I-like HLA antigen that is only sparsely distributed on the cell surface, lacks classical polymorphic determinants, and consists of heavy chains of lower molecular weight than those of classical HLA in association with beta 2-microglobulin (beta 2M). The latter two features are in general agreement with a previous report describing the nature of the HLA molecule on trophoblast disaggregated from term amniochorion. These cultured trophoblast cells could be useful for molecular studies of the unusual class I antigen, as well as for other in vitro experiments designed to mimic the in vivo local trophoblast-uterine interactions.