Equine trophoblast as an immunological target.

A cytotoxic T-lymphocyte assay was used to determine whether equine chorionic girdle cells are susceptible to lysis by CD8+ cytotoxic T cells primed in vitro against allogeneic lymphocytes. Classical cytotoxic T-lymphocyte activity against fresh or cultured trophoblast targets was demonstrated using peripheral blood lymphocytes from nonpregnant mares. Lysis of allogeneic (horse) and xenogeneic (donkey) lymphocyte targets was used as a control for trophoblast lysis. The major histocompatibility complex (MHC) class I specificity of the cytotoxic T-lymphocyte reactions was determined using panels of MHC-typed target cells. The results of the present study demonstrate that the MHC class I antigens expressed on equine chorionic girdle cells are functional proteins, which can serve as targets for CD8+ allospecific cytotoxic T lymphocytes. Furthermore, these findings indicate strongly that, at least in the in vitro assay used, MHC class I positive chorionic girdle cells do not display any mechanisms that can protect them from lysis by activated maternal T cells.