2.3 Measurement of serum sCD25 and cytokine levels
Peripheral blood samples were collected from LCH patients at the time of initial diagnosis and one week after treatment in available patients. Serum samples were separated by centrifugation at 1000 g for 20 min within four hours of blood collection. Processed samples were either immediately analyzed or stored at −80˚C until use. Serum levels of sCD25 were measured in duplicated using a specific Enzyme-linked immunosorbent assay (ELISA; Kindstar Globalgene Technology Inc.). Serum cytokine levels of interferon-γ (IFN-γ), tumor necrosis factor α (TNF-α), IL-10, IL-6, IL-4, IL-2 were determined by Cytometric Bead Array (Human Th1/Th2 Cytokine Kit II, BD Biosciences), as described previously31.