Garcia De Vinuesa, Maria CarolaTangye, Stuart GMoser, BernhardMackay, Charles R2015-12-131474-1733http://hdl.handle.net/1885/84352T-cell help for B cells is essential for high-affinity antibody responses and B-cell memory. Recently, the identity of a discrete follicular population of T cells that has a crucial role in this process has become clearer. Similar to primed CD4+ T cells in the tonsils and memory CD4+ T cells in the peripheral blood, this follicular population of T cells expresses CXC-chemokine receptor 5 (CXCR5). Owing to their distinct homing preferences and helper function, these T cells differ from T helper 1 and T helper 2 cells and have been denoted follicular B helper T cells. Here, we outline the central role of this subset in normal and pathological immune responses.Keywords: CD40 ligand; chemokine receptor CCR5; interleukin 10; transcription factor; antibody response; autoimmunity; B lymphocyte; cell differentiation; cell growth; cell maturation; cell migration; cell survival; cellular immunity; gene expression; gene mutation200510.1038/nri17142015-12-12