CD137L induces the release of immunosuppressive cytokines by AML cells. AML cells of patients with more than 80% blasts were cultured alone, on immobilized CD137-Ig or on human IgG1 as control. Levels of the indicated cytokines in culture supernatants were determined by ELISA. (A) Results of 10 investigated patients are shown. Horizontal bars represent the mean of the results obtained with each indicated culture condition. (B) Exemplary results (means of triplicates with SDs) with AML cells of single patients (□ indicates untreated; , human IgG1; ■, CD137-Ig). (C) Correlation between CD137L SFI levels and cytokine production upon CD137-Ig stimulation. Numbers in diagrams represent the UPNs of the patients used. *Statistically significant differences.