CHAPTER XIX 



HYPERSUSCEPTIBILITY 



THE phenomena now grouped together under the heading of 

 anaphylaxis and hypersusceptibility have but recently become the 

 subject of systematic experimentation. Nevertheless, manifestations 

 now recognized as belonging to this category had not escaped the 

 attention of a number of the earlier workers in immunity. 



Although the development of scientific knowledge of hypersus- 

 ceptibility has concerned itself particularly during the last fifteen 

 years with hypersusceptibility phenomena as they apply to antigenic 

 substances, we must deal with the subject a little more compre- 

 hensively than this at the present day, and call attention to the 

 fact that clinicians had for many years noticed so-called idiosyn- 

 crasies against drugs of various kinds, morphin, strychnin, arsenic, 

 etc., etc., and against many things which cannot be regarded at the 

 present time as antigens in the sense in which this term is used in 

 immunological literature. 



By hypersusceptibility in general, then, we mean that a certain 

 individual, human being or animal, suffers injury from the admin- 

 istration of a substance which, in similar amounts and methods of 

 administration, does not exert any injurious action upon normal 

 members of the same species. 



In some cases, such as pollen hypersensitiveness and some other 

 food idiosyncrasies, the hypersusceptibility may be congenital, that 

 is, inherited by the individual without traceable previous contact 

 with the substance to which he is sensitive. 



In most instances, however, some form of previous physiological 

 contact with the particular substance seems to be necessary for the 

 development of the hypersensitive state. 



Owing to the varied manifestations of specific hypersusceptibility, 

 it has been necessary to classify the phenomena of this nature into 

 two main subgroups. In doing this we follow the classification of 

 Doerr. 1 Doerr has grouped together all phenomena of hypersus- 



1 Doerr, Kolle and Wassermann Handb., 2, 1913, 947. 



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