Exosomes take (germinal) center stage.

Efficient antibody production is a crucial step during immune responses leading to pathogen clearance and neutralization. Immune synapses, contact points between T and B lymphocytes in the presence of an antigen, are necessary to initiate the proliferation and differentiation of B cells in the germinal center. In this issue of EMBO Reports, Fernández-Messina et al [1] present evidence of microRNA transfer from T to B cells via exosomes during synapse formation and highlight the crucial role of these exosomes for germinal center formation and the efficient production of antigen-specific antibodies.