How T cells earn the follicular rite of passage

Abstract

The discovery that Bcl-6 was the transcriptional regulator of follicular helper T (Tfh) cells completed the recognition of this population as an effector subset specialized in the provision of help to B cells. Improved reagents and recent models that allow tracking of Bcl-6-expressing T cells have revealed that the decision to become a Tfh cell occurs soon after T cells are primed by dendritic cells and start dividing, before interaction with B cells. The latter are important for sustaining Bcl-6 expression. Bcl-6 coordinates a signaling program that changes expression or function of multiple guidance receptors, leading to Tfh cell localization within germinal centers. This program is not unique to CD4 + helper T cells; FoxP3 + regulatory T cells and NKT cells co-opt the follicular differentiation pathway to enter the follicle and become specialized follicular cells. This review will focus on recent insights into the early events that determine Tfh cell differentiation. Show more