Hemolytic factors in Schistosoma japonicum eggs

Extracts of Schistosoma japonicum eggs were found to exhibit hemolytic activity on erythrocytes of various species. The hemolytic reaction took place more rapidly at 37 degrees C than at 4 degrees C and did not require divalent cations. The degree of hemolysis was dependent on the concentration of the egg extracts. The hemolytic factors seemed to be lipid in nature because of being heat-stable and soluble in chloroform solvent. Further analysis by means of thin-layer chromatography showed that hemolytic activity in the extracts was due to free fatty acids. Analysis by gas chromatography revealed that fatty acids in the egg extracts consist of myristic, palmitic, palmitoleic, stearic, oleic, linoleic, linolenic, and arachidonic acids. Among them, based on the experiments with commercially available fatty acids, arachidonic acid was the most intensively hemolytic, followed by linoleic, linolenic, oleic, palmitoleic, and myristic acids in that order, whereas palmitic acid showed weak activity only in the presence of divalent cations. From the estimated calculation, it was assumed that 1 mg of protein of the egg extracts contains as much as 0.22 mg of free fatty acids.