T-regulatory lymphocytes in peripheral blood of gastric and colorectal cancer patients.

AIM: To assess the absolute number of T-regulatory cells (Tregs; CD4+CD25+Foxp3+) in the peripheral blood of gastric and colorectal cancer patients.
METHODS: We enrolled 70 cancer patients (33 gastric cancer, 37 colorectal cancer) and 17 healthy volunteers. The CD3+CD4+ lymphocytes and CD4+CD25+Foxp3+ Tregs in the peripheral blood were analyzed with flow cytometry. The absolute numbers of Tregs were calculated based on the CD4+CD25+Foxp3+ cells percentage of CD3+CD4+ cells and the absolute numbers of CD3+CD4+ cells per microliter.
RESULTS: The mean number of CD4+CD25+Foxp3+ cells per microliter in colorectal cancer patients was 15.7 (SD: 21.8), for gastric cancer patients 12.2 (SD: 14.3), and for controls 17.5 (SD: 11.4). The absolute number of Tregs was significantly lower in gastric cancer patients than in controls (P = 0.026). There was no statistically significant difference for gastric vs colorectal cancer or colorectal cancer vs controls. The absolute number of Tregs was also significantly depressed in N+ vs N⁻ cancer patients [22.0 (27.7) vs 10.1 (9.0), P = 0.013], and in the subgroup of gastric cancer patients [30.3 (27.6) vs 9.6 (8.0), P = 0.003]. No statistical difference was observed in the proportion of Tregs in the CD4+ population between the groups.
CONCLUSION: The absolute number of Tregs in peripheral blood of gastric cancer but not colorectal cancer patients was significantly decreased in comparison with that in healthy controls.