Fig. 5

Increased infiltration of regulatory T cells in Kenyan breast cancer tissue. a Data analysis comparing the noncancerous and cancerous samples stained for CD25+ regulatory T cells. A significant increase was seen in regulatory T cell infiltration in the cancer samples, as shown by a higher percentage of positively stained cells (P = 0.03; Mann-Whitney), increased number of positively stained cells per area (P = 0.01; Mann-Whitney), and a higher percentage of CD25 stain per area (P = 0.0001; Mann-Whitney). Because the graph is a log scale, any samples with unstained sections (i.e., zero) are not included in the graph. The bar represents the median of all samples in the indicated cohort and includes any unstained samples. b Representative cancer and not cancer tissue samples stained for CD25. c Proposed T cell mechanism of action in Kenyan breast cancer model. (Top) Without a strong presence of regulatory T cells (e.g., benign Kenyan tissue), cytotoxic and T helper cells are able to combat and suppress the cancer cell, leading to increased apoptosis and loss of proliferation. (Bottom) When T regulatory cells are present (e.g., Kenyan breast cancer tissue), they block cytotoxic and helper T cells from fighting off the cancer cells