Figure 10.

CD4⁺CD25⁺ T cells from naive mice suppress preactivated effectors of concomitant immunity. CD8 immune T cells were generated as described in Fig. 6. (A) Incidence of B16 tumors in RAG1 ^−/− mice that had been previously (day −1) reconstituted with CD8 immune T cells or CD8 immune T cells mixed with various potential suppressor populations as follows: naive CD4⁺CD25⁺ T cells, CD4⁺CD25⁺ T cells from day-12 tumor-bearing mice, or CD4⁺CD25⁻ T cells from day-12 tumor-bearing mice. As determined by log rank analysis, the difference between tumor incidence in mice receiving immune CD8 cells alone and those receiving immune CD8 cells combined with naive CD4⁺CD25⁺ T cells was statistically significant (P = 0.0026). However, there was no statistical difference for mice cotransferred with tumor-bearing CD4⁺ CD25⁻ T cells (P = 0.992) or tumor-bearing CD4⁺CD25⁺ T cells (P = 0.677). Naive versus tumor-bearing CD4⁺CD25⁺ T cells did not reach statistical significance (P = 0.0729). (B) Tumor growth curves depicting growth rates of individual tumors in each group of adoptively transferred mice.