CHAPTER XVII. 

 ANAPHYLAXIS. 



Introduction. Proteid Hy per susceptibility . Anaphylaxis. Passive Anaphy- 

 laxis. Anaphylatoxin. Serum Disease. Hay Fever. 



The explanation for many phenomena discussed in the former chapters 

 was based upon the observation that by overcoming an infectious disease 

 the organism undergoes some transformation whereby it becomes refrac- 

 tory or less susceptible to the same infection. This changed state, demon- 

 strated neither by chemical nor microscopical methods, was termed 

 "Immunity." The most constant evidence of immunity is the presence 

 of antibodies. This, however, should by no means imply, as is so often 

 done in literature, that the demonstration of antibodies and the exist- 

 ence of immunity are identical. 



On the contrary, attention has already been called to the possibility of 

 paradoxical reactions. Animals or individuals in whom a grade of immu- 

 nity is expected, show instead a certain susceptibility toward the particu- 

 lar antigen. This altered reaction of the organism was termed "Hyper- 

 susceptibility" and "Anaphylaxis" (to distinguish it from prophylaxis- 

 immunity). The "paradoxical reaction" was discussed under diphtheria 

 where it was mentioned that horses immunized for a long period of time 

 would suddenly become severely ill after the injection of small doses of 

 toxin. The tuberculin reaction was another instance of such hypersensi- 

 tiveness. Infection by the tubercle bacillus not only made the body highly 

 sensitive toward the bacteria and their derivatives (tuberculin), but a 

 severe and characteristic reaction always took place as the expression of 

 this increased sensitiveness. 



In recent years, experimental studies have proven that this peculiar 

 phenomenon is not based upon entirely new laws, but that anaphylaxis 

 has as its governing influences principles that are closely related to those 

 influencing the process of immunity. It is still to be determined whether 

 the hypers usceptibility observed with various antigens like the pure toxins, 

 the tuberculins, and the proteids all follow the same biological mechanism. 

 The author is of the opinion that just as there are various forms of immu- 

 nity so also must the existence of various forms of anaphylaxis be presumed. 

 At least a cellular and humoral variety seem distinctly plausible; the 

 tuberculin reaction is an example of the former, the proteid anaphylaxis 

 of the latter. 



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