Figure 4. B16 melanoma TILs contain a high frequency of CD4⁺ and Foxp3⁺ but few CD8⁺ T cells.

The percentage of CD4⁺Foxp3⁺ T cells (A) and CD4⁺Foxp3⁺CD25^– T cells (B) was analyzed by flow cytometry of lymph nodes from naive and tumor-bearing mice 15 days after tumor challenge. In a parallel set of studies, lymph nodes (C) and tumors (D) from tumor-bearing mice were analyzed at day 15 for their content of CD8⁺, Foxp3⁺, and CD4⁺ T cells. (E) The ratio of CD4⁺Foxp3^– to Foxp3⁺ T cells (filled circles) and CD8⁺Foxp3^– to Foxp3⁺ T cells (open circles) was calculated and compared in tumors and lymph nodes from tumor-bearing mice 15 days after tumor challenge. The data represent cumulative results from 3 independent experiments with 3–5 mice/group.