CHAPTER IX 



CHEMICAL MEANS OF DEFENSE AGAINST NON- 

 ANTIGENIC POISONS ' 



Although the examples of acquired immunity against poisons of 

 known chemical composition are 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 immunity 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 (Haus- 

 mann) ; dogs can be made tolerant to only about 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 symptoms chronic poisoning is taking place; and, of course, 

 with many poisons no distinct increase of tolerance can be produced. 

 True immunity, associated with the production of neutralizing sub- 

 stances in the blood, has as yet been obtained only against substances 

 of protein nature or substances very closely resembling the proteins. 

 Ehrlich - believed that simple toxic chemicals are, like toxins, bound 

 to the cells by special receptors, cJienioreceptors, which, in view of 

 their simpler function may be assumed to be simpler than the re- 

 ceptors 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 by immunization. To be sure, there 

 have been observations interpreted as evidence of immunity to large 

 molecular complexes, especially such as lipoids and glucosides, but 

 as yet the positive establishment of the formation of antibodies by re- 

 action to non-protein antigens has not been accomplished. It must be 

 taken into consideration, however, that various chemical substances in- 

 troduced 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 hypei*sensitive ; in this way are ex- 

 plained the instances of idiosyncrasy, with reactions of anaphylactic 

 charapter, which are sometimes shown with iodoform, antipyrine, sal- 

 varsan, and other substances. (See Chapter vii.) 



Studies on bacterial immunity and allied topics have as yet shown 



1 Bibliography by Haiismann, Ergebnisse Physiol., 1907 (6), 58. 



2 Beitriige z. exp. Path. u. Chem., Leipzig, 1909, p. 189. 



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