ACTION OF COMPLEMENT IN THE LYSIS OF MOUSE SARCOMA CELLS SENSITIZED WITH H-2 ALLOANTIBODY

Abstract

A modified cytotoxicity assay was adapted from classical erythrocytolytic assays, in which complement [C] components were added in sequence to antibody-sensitized cells. This assay was applied to a model system in which mouse sarcoma cells were sensitized with H-2 alloantibody. The stepwise presentation of C components combined with the stabilization of C2 by I treatment considerably augmented the lytic efficiency of human C. More generally, the techniques adopted for this study provide a new model for obtaining basic information about selective reaction steps concerned in lysis of nucleated cells by alloantibody and C. Comparisons of the lysis of sheep erythrocytes by xenoantibody with the lysis of mouse sarcoma cells by H-2 alloantibody, in this assay system with oxidized or untreated human C, disclosed a difference in the kinetics of C142 formation, manifest in a lag phase and a protracted tmax [time of maximal formation of C142] for the sarcoma cells. Multiple C-mediated functional lesions are apparently necessary for immune lysis of nucleated cells.