CD137 signaling suppresses the suppressive function of treg cells of peripheral blood from breast cancer patients

Objective: To explore the biological effect of CD137 and its molecular mechanism on CD4+ CD25+ Treg cells. Methods: Anti-CD137 mAb was added to stimulate the T cells that isolated from peripheral blood of breast cancer patients and activated by PHA. T cell proliferation was determined by cell counting or by 3H-TdR incorporation assessing at the 3rd. The phenotype of cells was determined by FACS, and Foxp3 analysis was performed after fixation and intracellular staining. Cytokine in the supernatant was quantified with ELISA. Results: CD137 expressed on CD4+ CD25+ Treg cells. Triggering CD137 signaling of CD4+ CD25+ Treg cells by anti-CD137 mAb could promote the proliferation of T cells form PBMCs of breast cancer patients and decrease the ratio of Foxp3+ Treg population and reduce Foxp3 expression of Treg cells, as well as the production of TGF-β1 and IL-10, and suppress the ability of Treg cells to inhibit proliferation of CD4+ CD25-T cells. Conclusion: CD137 signaling could suppress the suppressive function of Treg cells, and CD137 might be a potential molecular target for the immunological interference. (authors)