Increased cTFH function in patients with active cGVHD. Frequency of plasmablasts (CD27^hiCD38^hi B cells) was measured after naive B cells were cultured with cTFH in the presence of SEB for 6 days. Circulating TFH were purified by cell sorting (purity >95%) from fresh patient samples and cultured with autologous naive (IgD⁺CD27⁻) B cells (Auto B) or naive B cells from an allogeneic healthy donor (Allo B). Results are compared for cTFH obtained from patients with no cGVHD (n = 6, for the autologous condition; n = 5 for the allogeneic condition) or active cGVHD (n = 8 for the autologous condition; n = 5 for the allogeneic condition). Black bars represent median values for each group. Exact Wilcoxon rank-sum test was used. *P < .05.