Dissecting CXCR5+ T cell populations--on the quest for a better understanding of B cell help during T dependent antibody responses

Abstract

High affinity antibody responses against protein antigens critically depend on T cell help during the germinal center reaction. So called follicular helper T cells (T(FH)), present in the germinal centers of human tonsils, have been characterised by the expression of CXCR5; however, only subgroups of the heterogeneous CXCR5 T cell population strongly support antibody production. A paper in this issue of the European Journal of Immunology demonstrates that high expression of the inducible co-stimulator (ICOS) molecule, rather than CD57, correlates with the follicular helper function. This result represents another step towards a better understanding of the complexity of the different T cell subpopulations participating in the germinal center reaction.