Neutralization of IFN-γ, and depletion of NK1.1⁺ or Gr-1⁺ cells in vivo leads to enhanced tumor growth. C57BL/6 mice (n = 10) were treated with PBS (), isotype-matched control mAb (□), a neutralizing anti–IFN-γ mAb (A, ■), a depleting anti-NK1.1 mAb (B, ■), or an anti–Gr-1 mAb (C and D, ▴) and were inoculated subcutaneously with either RMA-S (A,B,C) or RMA lymphoma cells (D). (A-D) Tumor growth was monitored and is presented as mean plus or minus SD. Asterisks indicate statistical significance of P < .01, determined by a one-way analysis of variance (ANOVA) test. One representative experiment of at least 2 independent experiments is shown.