362 HEMOLYSINS 



were more or less directly injurious, and incapable of replacing human 

 blood. In 1875 Landois demonstrated experimentally that while trans- 

 fusion of blood from one animal to another of a different species may 

 prove injurious and even fatal, transfusion to an animal of the same or of 

 very closely related species produced no ill effects. The explanations 

 offered were inadequate, until later researches on the hemolysins showed 

 that the normal blood-serum of one animal may contain hemolysins for 

 the erythrocytes of other animals, and, consequently, upon transfusing 

 this blood to another animal the hemolysin acting with the complement 

 present produced hemolysis in vitro, thereby explaining in part the tox- 

 icity of the alien blood. 



In 1898 Belfanti and Carbone made the observation that the serum 

 of a horse receiving several injections of rabbit blood was toxic for rab- 

 bits, whereas normal horse serum was without injurious effects. 



At about the same time Bordet published his epoch-making discov- 

 eries. He observed that while normal guinea-pig serum had little or 

 no hemolytic action on rabbit ery^irocytes, the serum of a pig that had 

 received a few intraperitoneal injections of rabbit blood was able quickly 

 and completely to hemolyze rabbit blood, just as an animal may acquire, 

 through immunization with cholera, the property of dissolving cholera 

 vibrios. He demonstrated further that this acquired hemolytic activity 

 was highly specific, for when animal A was immunized with the corpuscles 

 of animal B the serum of A acquired the power of hemolyzing only the 

 erythrocytes of B, and possibly of other animals closely related zoologic- 

 ally. It was found also that the hemolytic activity of an immune serum 

 was lost by age or could be removed by heating; that in either case the 

 serum could be reactivated by the addition of a little normal serum or 

 peritoneal exudate phenomena closely resembling that observed in 

 bacteriolysis, and due to the action of a thermolabile body or alexin and 

 a second and specific thermostabile antibody named by Bordet the 

 "substance sensibilisatrice." 



These observations were soon confirmed by Landsteiner and von 

 Dungern, and were followed by very extensive studies by Ehrlich and 

 Morgenroth, who likewise confirmed Bordet's experiments, but offered a 

 different explanation for the mechanism of the phenomenon, according 

 to the side-chain theory, and renamed the alexin and sensitizing sub- 

 stance concerned in the process " complement" and " hemolytic ambo- 

 ceptor" or "immune body," respectively. 



Definition. Hemolysins [Gr., al^a = blood + \vtiv = to dissolve] 

 are antibodies in a serum that, when acting with complement, have the 



