Expression of B7-H2 on CD8+ T cells in colorectal cancer microenvironment and its clinical significance

The knowledge about B7-H2 expression in tumor is growing, but many questions remain unresolved. Especially in human tumor microenvironment, little studies were done. To explore the expression and clinical significance of B7-H2 on T cells in colorectal cancer microenvironment, fresh tumor tissues and paired non-tumor tissues collected from 25 patients with colorectal cancer were made to research B7-H2 expression on the infiltrating T cells including CD8(+) T cells and CD4(+) T cells. Also, tumor bearing mice were sacrificed on day 5, day 10, day 15, day 20, day 25 and flow cytometry was used to analyze B7-H2 expression on CD8(+) T cells and CD4(+) T cells in mouse tumors and spleens. Then, it was found that B7-H2 expression on CD8(+) T cells in patients' tumor tissues was significantly higher than in non-tumor tissues. The expression of B7-H2 on CD8 (+) T cells in tumor microenvironment was significantly higher in patients with age <= 60 years old and the stage I-II. The expression level of B7-H2 on CD8(+) T cells in mouse tumors and spleens both reached the highest level at the early stage of inoculation (on day 5), decreased to the lowest level on day 10 and day 15 separately, and then gradually increased. In mouse spleens, B7-H2 expression on CD8(+) T cells was all significantly higher than on CD4(+) T cells in five time periods. So, in this study, it was found that B7-H2 expression on CD8(+) T cells in tumor micro-environment was closely related to the progression of colorectal cancer.