Tumor cells expressing HLA-G constitutively grow in immunocompetent mice. (A) Groups of 3 Balb/c mice were injected subcutaneously with 10 × 10⁶ Fon⁻ or Fon⁺ cells at day 0, and tumor growth was monitored at the indicated time points. Data represent the means ± SD from 1 representative experiment of 3. Inset shows the cell-surface expression of HLA-G1 by Fon⁻ and Fon⁺ cells and isotype controls. (B) Phenotypic analysis of PBMCs was performed at day 22, as described in the legend to Figure 4. Data are from 1 representative experiment of 2. (C) Proliferation of mononuclear cells of lymph nodes (LN), spleens, and peripheral blood (PBMC) was assessed as described in the legend to Figure 2 in response to Fon⁻ or Fon⁺ cells. Results represent the means ± SD of triplicates from 1 representative experiment of 2. The numbers indicated between parentheses are the P values. *P < .05; **P < .001; ***P < .005. (D) Levels of cytokines in plasma of naive mice or mice injected with tumor cells were quantified by ELISA. Fon⁺ tum⁺ indicates plasma collected at day 4; Fon⁺ tum⁻, plasma collected at day 21.