BAFF production is significantly increased after BMT in mice that develop cGVHD. (A) Plasma BAFF levels measured by enzyme-linked immunosorbent assay (ELISA) over time after BMT in cGVHD mice (BM + Sp), nondisease control mice (BM only), and C57BL/6 recipients of C57BL/6 BM + Sp Syn-BMT mice. Data shown are representative of 3 repeats; n = 15 (BM only group at day 8), n = 13 (BM + Sp at day 8), n = 10 (BM + Sp and BM only for other time points), and n = 5 (Syn). (B) Peripheral donor-derived B-cell numbers at day 20 post-BMT in recipients of μMT or WT donor cells. (C) BAFF levels measured by ELISA in plasma at day 20 after allo-BMT in recipients receiving donor cells from μMT or WT mice. In panels B and C, n = 10 in each group vs n = 9 in WT BM only group. (D) Soluble BAFF levels measured by ELISA at 3 time points (days 19, 42, and 61) after transplantation in recipients receiving BAFF KO BM only vs recipients receiving BAFF KO BM plus BAFF KO splenocytes; n = 10 in each group. (E) Body weight over time after allo-BMT in recipients of BAFF KO BM only or BM + Sp vs WT BM only or BM + Sp. Arrow indicates the median time of onset of ocular GVHD manifestations (day 30 post-BMT)⁴¹ ; n = 10 in each group. In panels D and E, we show 1 representative experiment of 3 performed. (F) Eye pathology score in recipients of BAFF KO BM only or BM + Sp vs WT BM only or BM + Sp. Total eye score shown includes combined scores for chemosis, mucoid discharge, and corneal opacity as determined in a masked fashion by Zeiss Stemi 2000-C stereo microscope examination at day 79 after allo-BMT; n = 10 (BM only) and n = 9 (BM + Sp). Bars of all data shown are mean ± standard error of the mean. Statistical analysis was performed by Kruskal-Wallis test (A,F), ordinary 1-way analysis of variance with Tukey’s multiple comparisons test (B-C), or unpaired Student t test with Welch’s correction (D) using GraphPad Prism 8 software. *P < .05, **P < .01, ***P < .001, ****P < .0001. NS, not significant (P > .05); T, T cells.