Elevated 2,3-diphosphoglycerate concentrations and alteration of structural integrity in the erythrocytes of Indian cases of visceral leishmaniasis.

The visceral leishmaniasis (VL) known as kala-azar in India is characterized by severe anaemia. The anaemia seems to be the result, at least in part, of the relatively short life-time of the erythrocytes, which have weakened cell membranes, possibly because of elevated concentrations of 2,3-diphosphoglycerate (2,3-DPG). There is a negative correlation (r = 0.91; P < 0.01) between erythrocytic 2,3-DPG concentrations and the blood concentration of haemoglobin, and the erythrocytes from infected patients display higher osmotic fragility than those from uninfected controls. Spectrofluorometry, using 1,6-diphenyl 1,3,5-hexatriene as a probe, indicated that fluorescence depolarization and microviscosity are also higher in the erythrocytic membranes from VL cases than in those from the controls. The cholesterol/phospholipid ratio is also relatively high in the membranes from the VL cases and there is degradation of the skeletal components and the major integral protein (band 3). The enhanced concentration of 2,3-DPG may be related to the altered structural integrity of the erythrocytes and this may lead to anisocytosis and the reduction in the erythrocytic half life.