Capillary leak syndrome associated with elevated IL-2 serum levels after allogeneic bone marrow transplantation

Summary The pathophysiological mechanisms involved in the development of a spontaneous systemic capillary leak syndrome (CLS) are unknown. In contrast, CLS is a well-known side effect of high-dose interleukin-2 (IL-2) therapy in solid tumors. We report on a patient who developed CLS with high serum levels of endogenous IL-2 under immunosuppressive therapy for chronic graft-versus-host disease (GvHD) after allogeneic bone marrow transplantation (BMT). Generalized edema persisted for 10 weeks. The condition resolved after antibiotic therapy of a septic shock with hemolyzing streptococci group A. Thus, a latent infection may alter cytokine homeostasis and may cause CLS in BMT patients.