Abstract

Maturation of B cells in Germinal Centers (GC) is a hallmark in adaptive immunity and the basis of successful vaccines that protect us against lethal infections. Therefore it is key to understand how B cell selection takes place in GCs in order to develop new and fully protective vaccines. The cellular mechanisms that control B cell selection are performed by different T cell populations. On one side, cognate interaction of B cells with T follicular helper (Tfh) cells promotes survival, proliferation, mutagenesis and terminal differentiation of GC B cells. On the other hand, regulatory T cells have also been reported within GC and interfere with T cell help for antibody production. These cells have been called T Follicular regulatory cells (Tfr). During this seminar, we will discuss the established phenotypes and functions of Tfh cells and Tfr cells, emphasizing the complementary role of these two cell populations in the GC.