CTLA4 and neoplasm: Consistent with the presence of robust immunologic memory that was not dependent on B cells or tumor-specific antibody, no tumor engraftment was observed in mice rendered disease-free with RT + IC + anti-CTLA-4 (0/14) or in those rendered disease-free with RT + IC + anti-CTLA-4 and subsequently depleted of B cell and plasma cells by anti-CD19 + anti-B220 (0/8) (Figure 3C).