THE EFFECTS OF PROTAMINE AND HISTONE ON ENTEROBACTERIAL LIPOPOLYSACCHARIDES AND HEMOLYSIS

Abstract

The effects of protamine and histone, basic simple proteins, on enterobacterial lipopolysaccharides were studied, utilizing the enterobacterial hemolysis test as indicator system. The latter is based on the fact that these antigens become readily attached to sheep erythrocytes and thus endow the latter with a new serologic specificity. As a result, hemolysis occurs upon the addition of homologous bacterial antibodies and guinea pig complement. It was found that protamine inhibits enterobacterial hemolysis by interaction with the antigen and prevention of attachment of the antigen to red blood cells. Protamine in like concentrations does not inhibit hemolysis of lipopolysaccharide-modihed red blood cells, nor docs it affect red blood cells directly. The inhibitory effect of protamine is abolished by trypsin treatment of the lipopolysaccharide–protamine mixtures. Histone, too, inhibits enterobacterial hemolysis. Its mode of action, however, is different from that of protamine, in so far as treatment of red blood cells with histone prior to lipopolysaccharide modification causes inhibition of hemolysis, conceivably because this protein either blocks red blood cell receptors or otherwise interferes with subsequent hemolysis. Furthermore, histone–lipopolysaccharide complex becomes attached to erythrocytes; specific hemolysis ensues after treatment of the latter with trypsin. The results of this investigation are discussed with particular reference to their bearing upon the biologic activities of lipopolysaccharides, namely, cell affinity, toxicity, pyrogenicity, and alteration of host resistance, notably via the properdin system.