Role of lipid peroxidation in dapsone-induced hemolytic anemia

Dapsone hydroxylamine (DDS-NOH) is a direct-acting hemolytic agent responsi ble for dapsone-induced hemolytic anemia in the rat. The hemolytic activity of DDS-NOH is associated with the formation of disulfide-linked hemoglobin adducts on membrane skeletal proteins. We have postulated that this membra ne protein "damage" is a consequence of DDS-NOH-induced oxidative stress wi thin the red cell and that it serves as the trigger for premature removal o f injured but intact red cells from the circulation by splenic macrophages. Oxidative stress has also been associated with the induction of lipid pero xidation, and it is possible that direct damage to the lipoidal membrane ma y play a role in the premature sequestration of the damaged cells in the sp leen. To investigate this possibility, rat and human red cells were incubat ed with hemolytic concentrations of DDS-NOH and examined for evidence of li pid peroxidation using two independent assays: thiobarbituric acid-reactive substances formation and cis-paranaric acid degradation. Phenylhydrazine, which is known to induce lipid peroxidation in red cells, was used as a pos itive control. The extent of thiobarbituric acid-reactive substances format ion and cis-paranaric acid degradation in DDS-NOH-treated rat and human red cells was not significantly different from that in control cells. In contr ast, thiobarbituric acid-reactive substances formation and cis-paranaric ac id degradation were significantly increased in red cells treated with hemol ytic concentrations of the positive control, phenylhydrazine. These data su ggest that lipid peroxidation is not involved in the mechanism underlying d apsone-induced hemolytic anemia.