The in vitro and in vivo functions of WAS patient Tfh cells or WAS KO Tfh cells. ELISA assay of IgG and IgM in the culture medium from HC naive B cells cocultured with HC or WAS Tfh cells (A) or from WT naive B cells cocultured with WT or WAS KO Tfh cells pulsed with SEB at day 3 (B). Flow cytometry analysis of GC B cells (C) or NP-specific GC B cells (D) from CD4 KO mice transferred with WT or WAS KO CD4⁺ naive T cells at day 7. The percentage and number of GC B cells (E) or NP-specific GC B cells (F) in CD4 KO mice transferred with WT or WAS KO CD4⁺ naive T cells at day 7. (G) The percentage and number of memory B cells in spleen of CD4 KO mice transferred with WT or WAS KO CD4⁺ naive T cells at day 7. (H) The MFI of CD86 in NP-specific B cells in CD4 KO mice transferred with WT or WAS KO CD4⁺ naive T cells. SSC, sidescatter.