Local activation of the killing mechanism in PU5 antibody-dependent cell-mediated cytotoxicity effector cells

Abstract

This study was undertaken to determine whether ADCC effector cells expressed their killing mechanism globally throughout the entire cell surface or locally in a restricted area. Nonantibody-coated erythrocytes were bound to PU5 ADCC effector cells by either Con A or protein A-Ig bridges, and the effector cells with the adherent nonspecific erythrocyte target cells were mixed with specific antibody-coated erythrocytes. Our results indicated that the Con A or protein A-Ig-linked erythrocytes were not destroyed while the effector cell was in the process of killing specific antibody-coated erythrocytes. Therefore, the ADCC killing mechanisms of PU5 cells require activation by the interaction of Fc receptor with specific antibody-coated erythrocytes, and these killing mechanisms, once activated, are expressed in a locally restricted area of the effector cells rather than globally throughout the entire surfaces of the ADCC effector cell. Previously, we investigated the expression of the killing mechanism in cytolytic T lymphocytes (CTL) and found that alloimmune CTL in the process of killing specific target cells did not kill nonspecific targets linked to the CTL by either wheat germ agglutinin or immunoglobulin bridges. Thus, with respect to the surface membrane expression of lytic activity, CTL and the PU5 ADCC effector cells are similar. Our findings support the view that the various effector killing cells have a common cytolytic pathway and differ only by the recognition and triggering mechanisms.