The frequency of different subsets of T cells. Following induction of colorectal tumors for 16 weeks, peripheral blood samples were obtained from individual rats and the frequency of CD3+, CD3 + CD4+, CD3 + CD8+ and CD3 + CD25+ T cells was characterized by flow cytometry analysis (A). At 21 weeks post induction, the rats were sacrificed and their peripheral blood (B) and splenic T cells (C) were characterized by flow cytometry analysis. Data are expressed as the mean ± SD of different groups of rats (n = 4 for the PBS group, n = 5 for other groups) from three separate experiments. *P < 0.05 SL3261R vs. PBS; #P < 0.05 SL3261R vs. SL3261; ^P < 0.05 SL3261R vs. SL3261C.