B-cell reconstitution in patients with stable/improved cGVHD after rituximab. (A) Serial measurement of total CD19⁺ B-cell number in patients with cGVHD who received rituximab at time 0 in 2 cGVHD groups (stable/improved = patients who required no further treatment 2 years after rituximab vs unresponsive = patients who required additional treatment 2 years after rituximab treatment for active cGVHD). (B) Comparison of the relative frequency of IgD⁺CD38^Hi “transitional” B cells before rituximab in the 2 cGVHD groups.