Compromised antitumor immunity in PLC-γ2-deficient mice. CFSE-labeled RMA cells and MHC class I-deficient RMA-S cells were coinjected intraperitoneally into 3 groups of mice and 48 hours later the peritoneal cells were stained with anti-H-2K^b (top row) or CD3 and NK1.1 (bottom row). Essentially only H-2K^b+ RMA cells were recovered from WT mice, H-2K^b- RMA-S cells being rejected by WT NK cells. Both types of tumor cells were recovered from Plcg2^-/- mice as well as from alymphoid Rag2^-/-Ilrg^-/- mice, suggesting that RMA-S cells were not cleared. The bottom row shows that NK cells are present in the peritoneal cavity of mutant mice. Data are from one individual mouse/group representative of 6 to 10 mice/group analyzed in 2 independent experiments.