The role of histocompatibility antigens in cell-mediated cytotoxicity against Marek's disease tumour-derived lymphoblastoid cell lines.

The cytotoxic activity of spleen cells from Marek's disease (MD) virus-infected chickens against syngeneic and allogeneic tumour cell lines was compared, using MD lymphoma-derived lymphoblastoid cell lines obtained from two inbred and two outbred chicken strains. Activity was significantly greater against allogeneic than against syngeneic target cells, although some activity against syngeneic cells was detected. Cold target cell inhibition tests confirmed that unlabelled normal spleen cells could block the cytolysis of tumour cell targets bearing the same histocompatibility antigens as the spleen cells. It was concluded that the tumour-specific antigens against which the effector cells were reacting may be modified histocompatibility antigens and that the enhanced cytotoxicity seen with allogeneic target and effector cells may be an artefact analogous to an adjuvant effect.