High BAFF levels and low B-cell numbers result in high BAFF/B-cell ratios in patients with cGVHD. Plasma BAFF concentrations and numbers of CD19⁺ B cells were measured in 3 groups after allogeneic HSCT: 22 patients with active cGVHD, 23 with inactive cGVHD, and 12 who did not develop cGVHD. Results were compared with 33 healthy donors. (A) Plasma BAFF concentrations in each patient group after HSCT and healthy donors. (B) Total number of CD19⁺ B cells in each patient group and healthy donors. (C) Median BAFF/B-cell ratio for each patient group and healthy donors. The BAFF/B-cell ratio was defined as nanograms of BAFF per 10³ CD19⁺ B cells. Box plots in each figure depict 75th percentile; median and 25th percentile values and whiskers represent maximum and minimum values.