BAFF promotes CD27⁺ pre-GC and PB/PC subsets in cGVHD. (A) In vivo correlation between soluble BAFF and numbers of CD27⁺ BCR-activated B-cell subsets is shown for patients with active cGVHD (top row) and patients with inactive cGVHD (bottom row). The total number of each CD27⁺ B-cell subset (Table 2) and the BAFF level (ng/mL) were natural log–transformed. (B) BCMA, TACI, and BAFF-R expression on pre-GC and PB/PC cells from a patient with active cGVHD compared with healthy control. Data are representative of 2 independent experiments conducted using 2 cGVHD patients and 2 healthy donors.