XI. ON THE MODE OF ACTION OF CYTOLYTIC SERA; 



AND ON THE UNITY OF THE ALEXIN IN 



A GIVEN SERUM.* 



BY DR. JULES BORDET. 



(From Professor Metchnikoff's Laboratory.) 



The conception that bacteriolysis by cholera serum and that 

 hemolysis by hemolytic sera are due to the combined action of 

 two distinct substances, as proved by us in 1895 and 1898, is now 

 generally accepted. These two substances are, first, the alexin, the 

 cellulicidal and bactericidal substance, properly speaking, occurring 

 in the serum both of normal and of immunized animals; and, second, 

 the specific sensitizing substance that endows an immune serum 

 with the particular property of favoring alexic activity. In collab- 

 oration with Dr. Gengou we have described in the preceding article 

 a method of demonstrating the existence of sensitizing substances. 

 This method depends essentially on the fact that a specific bac- 

 teriolytic or hemolytic serum heated to 55 degrees, and so deprived 

 of its own destructive power, will confer a bactericidal or hemolytic 

 power on normal alexic serum to which it is added. We further 

 demonstrated by a new method that these sensitizing substances 

 are present, certainly, in many, and probably in all, antimicrobial 

 sera resulting from artificial immunization. 



But the elementary fact that the destructive action of a serum 

 is due to the collaboration of the alexin and the sensitizer is not 

 sufficient. An attempt should be made to discover the inner 

 mechanism of the phenomenon and to determine the exact nature 

 of the reaction between the active substances and the affected cells. 

 It is only since 1899 that this new problem has been attentively 

 considered; the data obtained are not as yet very numerous and 

 yet three important facts have been firmly established. These 

 facts we shall enumerate and shall then consider the interpreta- 

 tions to which they have given rise. 



* Sur le mode d'action des scrums cytolytique et sur I'unitl de Palexine dans 

 un meme se>um. Annales de I'lnstitut Pasteur, XV, 1901, 303. 



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