CHAPTER X 



CHEMICAL MEANS OF DEFENSE AGAINST NON- 

 ANTIGENIC POISONS' 



Although the examples of acquired imniunity against poisons of 

 known chemical composition arc few indeed, nevertheless the body 

 possesses means of defense against many such poisons, which decrease 

 to greater or less degree their harmful effects. It is to be noted, how- 

 ever, that the increased tolerance to such poisons is far less than the 

 degree of tolerance characteristic of innnunity to true toxins; thus, in 

 arsenic eaters the maximum observed tolerance is but three or four 

 times the minimum, and less than the certainly fatal dose (Hausmann) ; 

 dogs can be made tolerant to only iibout three times the fatal dose of 

 morphine (Faust). Furthermore, with many poisons of this class the 

 tolerance is largely fictitious, since in spite of the absence of acute 

 svmptoms chronic poisoning is taking place; and, of course, with many 

 poisons no distinct increase of tolerance can be produced. True 

 immuniiy, associated with the production of neutralizing substances 

 in the blcod, has as yet been obtained only against substances of pro- 

 tein nature or substances very closely resembling Ihe proteins. Ehr- 

 lich- believed that simple toxic chemicals are, like toxins, bound to the 

 cells by special receptors, chemoreceptors, which, in view of their simpler 

 function may be assumed to be simpler than the receptors for toxins. 

 They seem to be more firmly fixed to the cells, and being, therefore, 

 less easily discharged than bacterial receptors no free antibodies are 

 produced bj^ immunization. To be sure, there have been observations 

 interpreted as evidence of imnumity to large molecular complexes, 

 especially such as lipoids and glucosides, but as yet the positive estab- 

 lishment of the formation of antibodies by reaction to non-protein 

 antigens has not been accomplished. It must be taken into considera- 

 tion, however, that various chemical substances introduced into the 

 blood or tissues of an animal, may form compounds with the animal's 

 proteins which behave like foreign proteins, to which the animal 

 reacts by becoming hypersensitive; in this way are explained the 

 instances of idiosyncrasy, with reactions of anaphylactic character, 

 which are sometimes shown with iodoform, antipj'rine, salvarsan, and 

 other substances. (See Antigens, Chapter vii.) 



Studies on bacterial immunity and allied topics have as yet shown 

 nothing to explain the acquirement of tolerance to morphine, alcohol 



' Bibliography by Hausmiinn, Ergebnisse Physiol., 1907 (6), 58. 

 ^ Beitrage z. exp. Path. u. Chem., Leipzig, 1909, p. 189. 



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