Desferrioxamine improves neutrophil phagocytosis in thalassemia major

The aims of the present study are: first, to assess the toxic role of serum from thalassemic patients in phagocytosis of PMN from healthy controls, and second, to seek to determine whether serum and cellular disturbances of polymorphonuclear neutrophils (PMN) phagocytosis, observed in thalassemic patients, can be prevented and/or corrected by use of desferrioxamine (DFX). Two kinds of in vitro incubations--without or with DFX--were performed. PMN or serum from thalassemic patients or from healthy controls was used. First, a phagocytosis defect of 3 different bacteria species was induced in PMN from healthy controls by incubation in thalassemic serum. Second, DFX could prevent, already at 1 microM, the phagocytic defect induced in normal PMN by the incubation with thalassemic serum, with disappearance of the toxic role of thalassemic serum at higher concentrations. Third, improvement of the phagocytosis defect of PMN from thalassemic patients was also observed at 1 microM of DFX for the 3 bacteria species. Normalization was obtained at higher concentrations for gram-negative bacteria. In vivo studies revealed, after a 3 hr subcutaneous infusion of DFX into 3 thalassemic patients, an improvement of the phagocytosis results and a decrease of the Prussian Blue reactivity of the PMN. It is concluded first that an iron-mediated defect in phagocytosis can be induced in normal neutrophils by incubation in serum from thalassemic patients, and second that a precautious and intensive chelation therapy seems to be advantageous for increasing PMN defense against infectious agents. Special care must nevertheless be taken in order to detect rapidly opportunistic (such as Yersinia) infections.