The prevalence of Th1, Th2, Treg, and Th17 cells in both peripheral blood mononuclear cells (PBMC) and gastric tissue was evaluated by multicolor flow cytometry. The concentration of interleukin (IL)-17 in sera was quantitated by enzyme-linked immunosorbent assay.
We observed a clear difference in the prevalence of Th17 cells in PBMC (0.34 ¡À 0.24 % ) versus gastric cancer tissues (19.4 ¡À 12.1) (P = 0.0002). Subset-specific phenotypic analysis of CD4+ T cells in both PBMC and gastric cancer tissue showed that Th1 and Treg cells predominate in PBMC, whereas Th17 cells are the most abundant CD4+ T cell subset in cancerous tissue. The concentrations of IL-17, a hallmark of Th17, in gastric cancer patients and normal controls were 0.6 ¡À 0.67 and 0.16 ¡À 0.19 pg/mL (P = 0.0032). Five-year survival rates of patients with high IL-17 and low IL-17 concentration were 47.1 % and 83.9 % (P = 0.0075). Multivariate analysis indicated that IL-17 concentration was an independent prognostic indicator, as well as lymph node metastasis.
There was a significant skewing toward a Th17 phenotype in gastric cancer tissue. IL-17 seems to play an important role in the progression of gastric cancer.