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 chi(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 Treg 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, Treg numbers correlate with both the CD8/CD4 ratio and the CD4/8 status, suggesting that Treg number is not a factor to predict patient's survival in OSCC.