CK18F but not sCD25 levels reflect response to immunosuppressive therapy in steroid-resistant disease. (A) Kinetics of CK18F levels in 4 patients with steroid-resistant GVHD: the lack of clinical response to high-dose steroid treatment is reflected in persistent or rising CK18F levels. (B) Kinetics of sCD25 levels in 4 patients with steroid-resistant GVHD: reduced sCD25 levels following steroid treatment despite of the lack of a clinical response.