CD4 and neoplasm: To further delineate the contribution of the host immune response to the anti-tumor effect of combination therapy, we treated tumor-bearing mice with depleting anti-CD4, CD8, NK1.1, or IFN-γ antibodies to eliminate, respectively, CD8+ T cells (Figure 4A,B), CD4+ T cells (Figure 4C,D), NK cells (Figure 4E,F), and IFN-γ (Figure 4G,H).