The role of CD20 T cells: Insights in human peripheral blood.

CD20 T cells constitute a small subset of T cells. These are found among CD4, CD8, CD4CD8, CD4CD8 T, and TCRγδ T cells, and have been poorly characterized. The aim of this study was to characterize peripheral blood (PB) CD20 T cells and compare them to their PB CD20 T cell counterparts. PB from 17 healthy individuals was collected. The distribution of CD20 T cells among maturation-associated T cells compartments (naïve, central memory, transitional memory, effector memory, and effector T cells), their polarization, activation status, and expression of immune-regulatory proteins were evaluated by flow cytometry. Their function was also assessed, by measuring IFN-γ, TNF-α, and IL-17 production. Compared with CD20 T cells, CD20 T cells represent a higher proportion of transitional memory cells. Furthermore, CD20 T cells display a proinflammatory phenotype, characterized by the expansion of Th1, Th1/17, and Tc1 cell subsets , associated to a high expression of activation (CD25) and exhaustion (PD-1) markers. In addition, the simultaneous production of the proinflammatory cytokines IFN-γ, TNF-α, and IL-17 was also detected in CD4CD20 T cells. Our results show that CD20 T cells are phenotypically and functionally different from CD20 T cells, suggesting that these cells are a distinct subset of T cells.