CD3 + CD20 + T cells and their roles in human diseases.

CD3+ CD20+ T cells are a population of CD3+ T cells co-expressing CD20 that make up to ∼3-5% of the CD3+ T-cell compartment in the peripheral blood of human beings. In healthy individuals, CD3+ CD20+ T cells are heterogeneous for containing a lower proportion of CD4+ cells, but produce higher levels of IL-17A and/or IFN-γ than those of CD3+ CD20- T cells. Recently, emerging studies have shown a pathogenic behavior of CD3+ CD20+ T cells in autoimmune diseases and CD20+ T-cell malignancies, and patients with the diseases may benefit from anti-CD20 immunotherapy to deplete these cells. However, CD3+ CD20+ T cells may also play a protective role in ovarian cancer and HIV infection for their strong propensity to IFN-γ production. In this review, we will describe the current knowledge about CD3+ CD20+ T-cell biology, and discuss their functional roles in autoimmune diseases as well as cancer and infectious diseases.