Fig. 3.

An antagonist of the IL-21 receptor (IL-21-R-antagonist) successfully inhibited peripheral follicular T helper (pTfh) cell functions in vitro. Memory B cells were co-cultured for 7 days with pTfh-cells in the presence of super antigen B. In addition, we added an IL-21-R-antagonist or an isotype IgG control to the co-cultures. After 7 days, we measured the percentage of memory B cells (Mem B) that survived; the percentage of memory B cells that differentiated into plasmablasts (PB); the IgM production (ng/mL); and the IgG production (ng/mL). Here a representative sample is depicted of the outcomes in the presence of an IL-21-R-antagonist compared with IgG control. The IgG isotype is set to 100 %. The concentration of IL-21-R-antagonist added was 5 μg/mL, corresponding to the IC50 [16••, 35]