Role of antibodies in the specificity of natural cell-mediated cytotoxicity.

Freshly isolated effector cells expressing natural cell-mediated cytotoxicity (NCMC) against cultured target cells possessed antibodies attached to Fc receptors on their cell surfaces. A wide variety of natural antibodies in the circulation combined with the receptors on effector cells to allow recognition of the many specificities on cultured target cells and resulted in reactions with an overall appearance of nonselectiveness. The role of antibodies in the specificity of NCMC was demonstrated by recovery of NCMC by trypsinized effector cells when incubated in serum. With absorbed serum, activity was selectively weaker against the absorbing target cell. When effector cells were reconstituted with antibodies eluted from the absorbing cells, selective cytotoxicity for that cell was detected. The specificity of effector cells reconstituted with eluted antibodies confirmed the results from previous studies on specificity by direct cytotoxicity and by competitive inhibition of cytotoxicity and supported the role of antibodies in NCMC.