Figure 4

cTfh cells from ETEC vaccinees promoted plasmablast formation and IgA antibody production. CXCR5⁺CD4⁺CD3⁺ cTfh cells, CXCR5⁻CD4⁺CD3⁺ T cells and memory B cells were sorted from PBMCs collected from three strong ALS responders before (preVacc) and after (postVacc) ETEC vaccination. cTfh or CD4⁺CXCR5⁻ cells were coincubated with memory B cells collected at the same time point and stimulated with SEB for 6 days. The frequencies of IgA⁺CD27⁺CD38^hi plasmablasts among CD19⁺ B cells (a) and the levels of total IgA (b), LTB-specific IgA (c) and total IgG (d) antibodies in culture supernatants were analyzed by FCM (a) or ELISA (b,c and d), respectively. Each symbol represents one subject (Subj.) and bars indicate median values (n = 2–3).