IL10 and breast cancer: Hence, Tfr cell differentiation might result from a balance between two opposing-effect cytokines, as their quantity and function are influenced by BCL6 or Blimp1 ablation.142,143 In breast cancer, Tfr cells inhibit B cell proliferation and antibody generation by IL-10.144 The number of CXCR5+FOXP3+ Tfr cells in the peripheral blood was higher in early-stage BC patients than in advanced-stage, implicating their involvement in tumor progression and invasion.145 Moreover, Tfr cells exhibit a low response to anti-PD-1 therapy.