A hemolytic factor from Haemonchus contortus alters erythrocyte morphology

A hemolytic factor from adult Haemonchus contortus caused distinct morpholo gical changes in the surface of sheep red blood cells (RBCs). After a 15 mi n exposure to the hemolytic factor, hemolysis was not detected in incubatio n media, but RBCs were spherical in shape with numerous surface projections compared to control cells that were smooth-surfaced biconcave disks. After 30 min, a time at which significant hemolysis occurred, echinocytes were f ormed, and after 90 min, cells were severely disrupted with many visible ho les in membranes. No RBC ghosts were observed. RBCs from four other mammali an species were lysed by the H. contortus hemolytic factor. However, the ra te of hemolysis varied with a relative order of sheep approximate to rabbit >goat>pig>calf. The morphology of RBCs from all four species was significan tly altered after 30 min incubation with the degree of morphological change s related to the degree of hemolysis. These results support the hypothesis that the hemolytic factor acts as a pore-forming agent, although a phosphol ipase or other enzyme might play a role in solubilization of cell membranes . (C) 1998 Elsevier Science B.V. All rights reserved.