Leishmania donovani: hemolytic activity of promastigotes

A hemolytically active component was found to be present in Leishmania donovani promastigotes for the first time. It lysed human and rabbit erythrocytes to varying degrees. The optimal pH for the activity was found to be 5.8. The rate of hemolysis was dependent on both erythrocyte and parasite concentrations. Parasites in the log phase were more effective in lysing erythrocytes than those in the stationary phase. Centrifugation at 10,000g showed major activity in the pellet fraction of the autolysate. Boiling in a water bath for 5 min reduced 98% of the hemolytic activity, which was also found to be inhibited by trypsin. The presence of such a hemolytic factor appears to be important in the nutrition of this parasite.