Structural similarities among malaria toxins, insulin second messengers, and bacterial endotoxin

Malaria toxin causes hypoglycemia and induction of tumor necrosis factor. Extracts of parasitized erythrocytes which were coeluted and copurified with one of the two subtypes of mammalian insulin-mimetic inositophosphoglycans similarly induced fibroblast proliferation in the absence of serum. In addition, induction of tumor necrosis factor in macrophages by malaria toxin and by lipopolysaccharide from Escherichia coli was enhanced by pretreatment of these toxins with alpha-galactosidase. Thus, parasitized erythrocytes contain both soluble inositophosphoglycan-like insulin second messengers and endotoxin-like lipid molecules.