Somatic hybrids between a high NK-sensitive lymphoid (YACIR) and several low sensitive sarcoma or L-cell-derived mouse lines exhibit low sensitivity.

Mouse somatic cell hybrids between a high NK-sensitive lymphoma line (YACIR) and various sarcoma or L-cell-derived cell lines (all weakly sensitive) all exhibited low NK sensitivity. This was not due to a general resistance to cell-mediated lysis, since these mouse hybrids could be killed by in vitro-sensitized specific T cells. Alloantigens are usually codominantly expressed in somatic cell hybrids, whereas differentiation-related markers are usually suppressed. Because NK sensitivity was found to be suppressed, in contrast to the expression of alloantigens and tumor-associated antigens, we suggest that the target structure may be either a differentiation-related antigen or a differentiation-related "membrane property."