Antibody-induced killing in vivo of L1210/MTX-R cells quantitated in passively immunized mice with 131I-iododeoxyuridine-labeled cells and whole-body measurement of retained radioactivity.

The killing of the LR subline of the DBA/2J leukemia L1210/MTX by passive antibody was followed in vivo with 131I-iododeoxyuridine-labeled cells and whole-body measurement of retained radioactivity. The in vivo killing of LR cells was proportional to the in vitro 2-mercaptoethanol resistant titer, independent of the complement system, and radioresistant. Although a large percentage of the leukemic cells was killed in passively immunized mice, the protective effect of the passive antiserum was dependent on the active immune response of the host.