Increased serum levels of macrophage colony‐stimulating factor (M–CSF) in α‐and β‐thalassaemia syndromes: correlation with anaemia and monocyte activation

Serum levels of M-CSF were determined by an ELISA method in 29 and 34 patients with HbH disease (alpha 1/alpha 2 or alpha 2/HbCS) or beta zero-thal/HbE, respectively, in 28 haematologically normal subjects and in five patients with anaemia due to iron deficiency or myelodysplasia. In HbH disease and beta zero-thal/HbE, M-CSF concentrations were significantly higher than those in the normal subjects [986 +/- 138 and 1385 +/- 133, respectively, vs. 500 +/- 33 pg/ml (mean +/- SEM); p < 0.01, and p < 0.001, respectively]. By contrast, in patients with anaemia due to iron deficiency, M-CSF levels were within the normal range. In HbH disease and in beta zero-thal/HbE, M-CSF levels correlated inversely with mean basal Hb values (r = -0.39, p = 0.05 and r = -0.60, p < 0.001, respectively). In addition, in some of the HbH and beta zero-thal/HbE patients, monocyte ADCC activities towards red cells were tested and found to be approximately twice as high as those in normal controls [38.3 +/- 5.7 and 30.7 +/- 4.6 vs. 17.8 +/- 1.8% specific lysis (mean +/- SEM), respectively; p < 0.01 and p < 0.02, respectively]. When thalassaemic patients and normal controls were considered together there was a significant correlation between M-CSF levels and monocyte ADCC activities (r = 0.51, p < 0.02). The results suggest that in HbH disease and in beta zero-thal/HbE, raised serum M-CSF contributes to the anaemia by enhancing the effector function of mononuclear phagocytes towards red cells.