304 INFECTION AND IMMUNITY 



factor which may possibly lead to further elucidation of phenomena of 

 hypersusceptibility. They have shown that, in passive anaphylaxis at 

 least, simultaneously with the occurrence of symptoms, there is a marked 

 diminution of complement in the serum of the treated animal. Intra- 

 venous injection of substances which prevent complement absorption in 

 vitro — concentrated salt solution, for instance — prevented anaphylaxis 

 in both actively and passively sensitized animals. They suggest that 

 sudden removal of complement from the circulation has a definite causal 

 relationship to anaphylaxis. 



Friedberger's more recent work has shown that the action of com- 

 plement in vitro, both upon bacteria and upon the precipitates formed 

 when a dissolved antigen is mixed with its antiserum, will produce 

 poisons which kill guinea-pigs in typical anaphylactic shock. His 

 results, much confirmed by his own work and that of others, seem to 

 indicate that anaphylactic shock may be due to a poison, "anaphyla- 

 toxin," which is formed by the proteolytic action of the complement 

 upon the foreign protein which is injected into the animal, and which is 

 sensitized to the action of the complement by the antibody formed in 

 response to the first injection. 



The toxic effects of Friedberger's "anaphylatoxins" are in many 

 ways similar to those of Vaughan's toxic-protein-split products, and the 

 subsequent development of his theory of anaphylaxis and infectious 

 disease may be logically regarded as a further elaboration of Vaughan's 

 views, though approached from a different point of departure. 



