Infiltrating regulatory T cell numbers is not a factor to predict patient's survival in oesophageal squamous cell carcinoma

CD4/8 status has been previously reported to be a critical factor in the prognosis of oesophageal squamous cell carcinoma (OSCC). In the current study, we investigated the effect of regulatory T cells (T(reg); Foxp3(+) lymphocytes) on the status of CD4(+) and CD8(+) T cells in 122 patients with OSCC. Immunohistochemical analysis of T(reg) was performed using an antibody against Foxp3. The survival rate for low Foxp3 patients was significantly lower than for high Foxp3 patients (P=0.0028 by log-rank test), but Foxp3 status did not significantly correlate with prognosis in CD4/8(+/+) patients or CD4/8(+/−) or (−/+) patients (P=0.5185 and 0.8479, respectively, by log-rank test). We also found that Foxp3 status correlated with CD4/8 status (P=0.0002 by χ(2) test) and that the variance of CD8/CD4 ratio in patients with low Foxp3 was larger than in patients with high Foxp3 (P<0.0001 by F-test). Thus, the results do not support the idea that T(reg) suppress anti-tumour immunity in patients with OSCC. Rather, the CD8/CD4 ratio and CD4/8 status appear to be critical factors in anti-tumour immunity. Furthermore, T(reg) numbers correlate with both the CD8/CD4 ratio and the CD4/8 status, suggesting that T(reg) number is not a factor to predict patient's survival in OSCC.