Presence of Syk in BM-derived B cells, but not donor T cells, is necessary for development of cGVHD pathology in a BO model. (A) Day-60 pulmonary function tests of mice transplanted with tamoxifen-induced Syk KO BM and WT T cells. (B) Frequency of B cells in transplanted mice on day 60 after transplant. (C) Pulmonary function tests from mice transplanted with WT BM and either WT T cells or Syk KO T cells. (D) Pathology scores from lung and liver of mice transplanted with Syk KO T cells. *P < .5; **P < .01. Error bars represent SEM; representative data from 3 independent experiments with n = 8 per group.