Interleukin (IL)-21 and IL-21 receptor expression in peripheral T and B cells of patients with breast cancer.

IL-21 is a cytokine with versatile antitumor and pro-tumorigenic activities. It is mainly produced by CD4+ T cells and B cells are one of its pivotal targets. In this study, we assessed and compared the expression of IL-21 by CD4+ T cells and the IL-21 receptor (IL-21R) on B cells in the peripheral blood of women with breast cancer and healthy individuals.