Effect of neoadjuvant chemotherapy on the tumor cell proliferation and peripheral blood T lymphocyte subsets of the III/IV interim low rectal carcinoma

Objective To investigate the tumor cell proliferation and peripheral blood T lymphocyte subsets amount in Ⅲ,Ⅳ interim low rectal carcinoma patients receiving neoadjuvant chemotherapy. Methods The cancer foci mucosae of 45 cases of Ⅲ,Ⅳ interim low rectal carcinoma were inspected to compare the change of tumor cell proliferation before and after chemotherapy. The blood samples from these patients were collected before and after neoadjuvant chemotherapy. Flow cytometry was applied to detect the CD3+,CD4+, CD8+ expression, lymphocyte apoptosis and necrosis in these samples. Results Proliferating cell nuclear antigen(PCNA)expression in rectal cancer tissue was lower in experimental group than in control group. The lowest expression occurred at 24 h after chemotherapy, and the expression at 7th- 10th d returned to the level before chemotherapy. At 2nd day after chemotherapy, the number of CD3+,CD4+, and CD8+ cells was significantly reduced as compared that at 1st day before chemotherapy[(32.19±2.89)% vs.(58.17±6.95)%, (22.32±2.72)% vs.(40.25±9.22)%,and(15.76±5.41)% vs.(23.72±3.62)%,P 0.05). At 5th day after chemotherapy, the number of CD3+ and CD4+ cells in peripheral blood was increased, ratio of CD4+/CD8+ was significantly increased [(4.55±1.31)% vs.(1.28±0.58)%], and number of CD8+ T lymphocytes was significantly decreased [(11.18±7.21)% vs.(23.72±3.62)%]as compared with those before chemotherapy(P< 0.05 for all). Conclusion Neoadjuvant chemotherapy can significantly inhibit the proliferation of tumor cells in rectal carcinoma. The appropriate interim period during the end of chemotherapy to surgery is 7- 10 days. Effective neoadjuvant chemotherapy may improve immune function in interim low rectal carcinoma patients by regulating the T cell levels in tumor microenvironment. Key words: Rectal carcinoma; Neoadjuvant chemotherapy; Proliferation; Lymphocyte subsets