Sickle cell disease (SCD) is recognized as a chronic inflammatory condition. Cytokines are released in response to stress or pathological situations, and influence hematopoiesis. The aim of this study was to evaluate interleukin-3 (IL-3), interferon-gamma (IFN-gamma), and neopterin (NP) levels in steady-state patients with sickle cell anemia (SS) (n = 35) and SC hemoglobinopathy (n = 15) in order to verify the possible action of those cytokines and NP on iron metabolism and hematopoiesis. Serum IL-3 concentration was higher in SS and SIC groups than in controls, whereas IFN-gamma levels did not differ among groups. SS patients presenting hemoglobin fetal (HbF) >= 8.5% had significantly higher IL-3 levels than those with HbF < 8.5% (P = 0.0338). No correlation was observed among inflammatory and iron metabolism parameters. Significant correlations were observed between IL-3 and Hb levels (r=0.4633, P=0.0457), and IL-3 and HbF levels (r=0.6011, P = 0.0065). A negative correlation was observed between IL-3 and reticulocyte counting (r = -0.4632, P = 0.0457) only in the SS group. NP levels were significantly higher in the SS and SIC groups than in controls, but did not differ between SS and SIC. No correlation was observed between NP and iron metabolism parameters. These data suggest that IL-3 stimulates hematopoiesis, and that SS patients, even in steady state, have macrophage/monocyte activation (represented by high levels of NP) that probably contributes to their chronic inflammatory condition.2037579