Antibodies against PDGF receptor in patients with extensive cGVHD. Levels of reactive oxygen species in mouse-embryo fibroblasts Fα (panel A) and F−/− cells (panel B) incubated with IgG (200 μg/mL for 15 minutes per 20 000 cells) from healthy subjects (N; n = 20), extensive chronic GVHD patients (ecGVHD; n = 22), and from patients who had not developed GVHD after transplantation (NoGVHD; n = 17). Fα cells were also pre-incubated with the selective inhibitors of PDGFR tyrosine kinase (AG 1296, 2 μM for 2 hours) and of the epidermal growth factor (EGF) receptor tyrosine kinase (AG 1478; 2 μM for 2 hours).