Germinal center helper T-cells are dual functional regulatory cells with suppressive activity to conventional CD4+ T-cells (92.1)

Abstract

Abstract Germinal center (GC) reaction is a T cell-dependent process in which activated B cells mature to produce high-affinity antibodies and differentiate into memory B cells. The GC microenvironment is almost exclusively reserved for the optimal antigen-specific B cell clonal expansion, selection and maturation, but lack of significant conventional CD4+ T- cell responses. The mechanisms that ensure such a focused B cell response in the GC are not known. Here we report that human CD4+CD57+T-cells, which are the major helper T-cells in GCs, actively suppress the activation of conventional CD4+ T-cells, particularly Th1 cells, via direct contact-dependent mechanism and soluble mediators. Our findings demonstrate that GC T-cells are unique regulatory cells that provide critical help signals for B-cell response but suppress conventional effector T-cells in the same local environment.