Early and late events in Streptolysin-O induced hemolysis

Treatment of erythrocytes with activated Streptolysin (SLO) resulted in a “swelling” of the target cells. The mean cell volume (MCV) of toxin treated human - sheep - and rabbit red blood cells increased by about 15% of the original value as measured in the Coulter Counter apparatus. Release of hemoglobin was influenced by the addition of high molecular weight colloids. In contrast ATP release was indipendent of the osmolarity and started before an increase in MCV was observed. The experiments indicated that “colloid osmotic lysis” is involved in SLO induced hemolysis.