Minor histocompatibility antigens are developmentally regulated on murine embryonal carcinoma cells and their early differentiated derivatives.

Differences in the expression of minor histocompatibility (Hm) alloantigens on two mouse embryonal carcinoma (EC) cell lines and the PYS-2 and T.D.M.-1 differentiated derivatives have been demonstrated by their ability to elicit a cytolytic T lymphocyte response. Experiments involving the use of various responder-target strain combinations and recombinant inbred mice strains have shown that: (1) there are major differences in Hm expression on EC cells compared with differentiated derivatives whose Hm expression appears more like that of adult splenocytes; (2) although both EC cell lines show reduced Hm immunogenicity compared with adult splenocytes, major differences in the expression and possible presentation of Hm between the F9 and PCC3 EC cell lines can be detected by in vivo priming and by in vitro cold competition target experiments. These observations are discussed in relation to the differences in allograft rejection patterns observed with PCC3 and F9 and to possible differences in developmental staging of these cell lines.