434 THE POPULAR SCIENCE MONTHLY 



SOME ASPECTS OF ANAPHYLAXIS 



By JOHN AUER, M.D. 



THE ROCKEFELLER INSTITUTE FOR MEDICAL RESEARCH 



THE word anaphylaxis is used to designate the train of symptoms 

 and signs which is produced by the incorporation of a foreign 

 soluble proteid into an animal organism which has already been sub- 

 jected before to the action of this same foreign proteid. The first injec- 

 tion need cause no obvious disturbance at all, and the injected animal 

 seems to be perfectly normal. But if this animal be reinjected after an 

 appropriate interval, it will answer with marked reactions, which may 

 even end in death. Thus, for example, 5 to 6 cubic centimeters of horse 

 serum injected intraperitoneally in a guinea-pig cause no more ap- 

 parent disturbance than the same quantity of physiological salt solu- 

 tion ; but if the same animal receive the same amount of the same horse 

 serum intraperitoneally after two or three weeks, the animal usually 

 dies in a short time. The first injection, therefore, though it caused 

 no obvious change in the animal, has profoundly altered its constitu- 

 tion, and it reacts on second injection as if the original substance were 

 now a violent poison. The animal, however, does not acquire this 

 remarkable property at once; approximately ten to fourteen days must 

 elapse before the second injection elicits marked toxic effects. If the 

 injection is repeated earlier, slight or no symptoms will be produced. 

 It is thus clear that the organism requires a certain length of time 

 before the second injection can call forth toxic symptoms. The whole 

 process, then, shows three distinct phases : 



(1) Sensitization, caused by the first injection of the foreign pro- 

 teid; (2) Incubation, the time which elapses before the second injection 

 can cause a response; and (3) the state of Intoxication which this 

 second injection causes when given to a sensitized animal. 



These three stages show some interesting points which deserve to be 

 mentioned more in detail. 



Sensitization. — Any soluble proteid may be used to sensitize an 

 animal, provided that it is of foreign nature ; nor need these proteids be 

 of animal origin ; Wells has recently shown that a large number of plant 

 proteins may be used for this purpose. 



The proteid usually employed in laboratory investigation, for ana- 

 phylaxis can only be studied by animal experiment, is horse serum, and 

 horse serum is used only because it is easily obtainable, and is not 

 poisonous to the ordinary laboratory animals on first injection. A 



