Protective antibody (Ab) responses induced by natural infection or vaccination play a central
role in defense against invasive pathogens. Germinal centers (GCs) are the sites of Ab
affinity maturation and T follicular helper (Tfh) cells are a critical factor for driving GC
formation and B cell selection. Therefore characterization of antigen (Ag)-specific Tfh cells is
increasingly essential to define the mechanistic basis of protective antibody responses.
However, since Tfh are weak producers of cytokines it is difficult to detect Ag-specific Tfh …