Immune properties of human teratocarcinoma. I. Human teratocarcinoma targets distinguish between natural killer and activated killer cells.

Four human teratocarcinoma (HT) cell lines were studied as a class of targets for natural (NK) and activated (AK) lymphocyte-mediated cytotoxicity. NK cells were found to be ineffective in lysing 51chromium-labeled HT targets. In contrast, alloactivated and mitogen-activated AK cells were highly cytotoxic for HT. The specificity of AK-mediated HT lysis was investigated by cold target competition experiments. The results showed that the target was shared by all HT lines tested but was not MHC related and was not present on lymphoblastoid cells (LBL) or on resting or activated normal lymphocytes. The demonstrated presence of unique fetal antigens on HT may provide an informative model for the study of AK target specificity and its functional relationship to differentiation.