CHAPTER X 

 HYPERSUSCEPTIBILITY 



DEFINITION. 

 OCCURRENCE. 



ANAPHYLAXIS. 



SENSmZATION. 

 PERIOD OF INCUBATION. 

 INTOXICATING INJECTION. 

 THE REACTION. 



CLINICAL PHENOMENA. 

 DISTENTION OF LUNGS. 

 FALL IN BLOOD-PRESSURE. 

 METABOLIC AND BLOOD CHANGES. 

 DECREASED COAGULABILITY OF BLOOD. 

 DESENSITIZATION. 

 PASSIVE ANAPHYLAXIS. 

 SPECIFICITY OF ANAPHYLAXIS. 

 THEORIES OF REACTION. 



ANAPHYLACTIC POISONS. 

 CELLULAR THEORIES. 

 PHYSICAL THEORIES. 

 ANAPHYLACTOID PHENOMENA. 

 SUMMARY. 

 THE RELATION OF ANAPHYLAXIS TO IMMUNITY. 



Definition. On casual consideration hypersusceptibility appears to 

 be a condition exactly the opposite of immunity. If by immunization 

 an animal becomes more than normally resistant to a poisonous or in- 

 fective agent so in the state of hypersusceptibility it is more than nor- 

 mally susceptible to poisons, to infective agents and to agents which in 

 the normal animal appear to be entirely innocuous. More critical 

 examination of the phenomenon, however, has led to the conception 

 that hypersusceptibility is but one manifestation of the intricate 

 mechanism of immunity. The reasons for this latter conception will 

 appear in the subsequent discussion. The term hypersusceptibility is 

 not to be confused with anaphylaxis, with which, in our judgment, it 

 is not synonymous. We prefer to limit the term anaphylaxis to that 

 state of hypersusceptibility to a given substance which has been induced 

 by a previous injection of the same substance. The reaction is limited 

 to proteins or protein fractions. Natural hypersusceptibility to non- 

 protein substances may occur, but this condition cannot be induced by 

 a previous administration of such substances. 



Occurrence. Hypersusceptibility may be natural or acquired. 

 Undoubtedly certain individuals in whom the condition is supposed to 

 be natural have acquired the state by preliminary inoculation of the 

 substance to which they are susceptible. This may be an unconscious, 

 forgotten or concealed acquisition. The introduction of practically any 

 protein into the tissues of the body may lead to the acquisition of a 

 hypersusceptibility of long duration unless the primary inoculation is 

 succeeded by others at proper intervals and in proper amounts to produce 

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