C-Reactive Protein as a Mediator in the Lysis of Human Erythrocytes Sensitized by Brown Recluse Spider Venom 1

Abstract

Abstract

Hemolytic reactions, frequently associated with envenomization by the brown recluse spider, Loxosceles reclusa, are poorly understood. Using an in vitro model some fundamental observations on venom-induced hemolysis have been characterized which indicate that C-reactive protein could be a mediator in the natural toxic process. Washed human type O erythrocytes, when added to small amounts of brown recluse spider venom, show no direct lysis; however, when added to normal fresh, blood group-compatible adult human serum, these venom-sensitized cells are destroyed. The ability to lyse cells is complement dependent, but individual sera show quantitative differences which are not related to the levels of functional complement. Fresh human cord sera contain adequate levels of complement but are unable to lyse venom-sensitized erythrocytes. Experiments were done in which reactive fresh adult human serum was immunoabsorbed with specific rabbit antibodies to human C-reactive protein. This absorbed human serum lost about 65% of the ability to lyse venom-sensitized erythrocytes. These results were highly suggestive that C-reactive protein played a role in this in vitro hemolytic reaction. Definitive experiments were done by adding measured amounts of purified human C-reactive protein to nonhemolytic fresh normal cord serum. Amounts as small as 0.192 μg/ml allowed this serum to become hemolytic. C-Reactive protein has recently been shown to activate complement, effect clotting mechanisms and influence T lymphocytes, properties which could be important in the regulation of immunopathological mechanisms. The observation that C-reactive protein plays a necessary role in the in vitro complement-dependent lysis of venom-sensitized erythrocytes suggests a possible role for this protein in natural human envenomation by the brown recluse spider.