Abstract: Objective To investigate the changes of CD4⁺CD25⁺ regulator T cells in peripheral blood from the paitents with lung cancer and breast cancer. Methods Flow cytometry was used to analyze the proportion of CD4⁺CD25⁺ T cells/CD4⁺T cells in peripheral blood mononuclear cells (PBMC) from 9 patients with lung cancer, 9 patients with breast cancer and 10 patients without cancer as controls. The expression of foxp3 mRNA in PBMCwas detected by RT-PCR. Results The value of CD4+CD25+ T cells/ CD4+T cells in PBMC from patients with lung cancer and breast cancer (21.30±11.26)% was significantly higher compared with controls (14.19±〖JP〗8.56)%. The expression of foxp3 in PBMC enhanced in patients with cancer compared with controls，there was significant difference between two groups (P<0.05). It revealed that the population of CD4⁺CD25⁺ regulator T cells in peripheral blood of patients with cancer was increased. Conclusion CD4+CD25+ regulator T cells may be responsible for immune suppression in the tumor immunity while maintenance of immune tolerance and the increase of CD4+CD25+ regulator T cells may be involved in tumor generation.

Key words: sup>CD25^+<, sup>T cell, foxp3, lung neoplasms, breast neoplasms