Variance in resistance to natural and antibody-dependent cellular cytotoxicity and to complement-mediated lysis among K562 lines.

Isolation of sub-populations of the NK-sensitive erythro-leukaemic cell line K562 by limiting dilution techniques has revealed marked clonal variation in susceptibility to natural cytotoxicity. Detailed examination of two such lines (E10/P2 and F9/P2) which differed significantly in their susceptibility to both native and activated NK-cell-mediated lysis revealed that their differences were stable and independent of culture conditions. The resistant (F9/P2) and sensitive (E10/P2) lines had comparable cold-inhibitory and effector-cell adsorption capacities, indicating that differential susceptibility was not attributable to variable expression of NK target structures. F9/P2 was also less susceptible to antibody-dependent cellular cytotoxicity (ADCC) and complement-mediated lysis, indicating the existence of variants with a generalized capacity to resist several immunolytic processes.