182 PROTEIN POISONS 



animals sensitized with heterologous or homologous tissue. 

 (7) A cutaneous reaction has not been obtained. 



This work is confirmed and supplemented by that of 

 Sata, 1 who sensitizes guinea-pigs with a single injection of 

 tuberculous serum, in doses of 0.1, 0.5, or 1.0 c.c. subcu- 

 taneously, intraperitoneally, or intravenously, and uses a 

 reinjection of old-tuberculin intravenously. When the 

 dose of the reinjection is as much as 0.5 c.c. acute ana- 

 phylactic death results. With smaller doses there is 

 elevation of temperature. 



Many investigators have failed to sensitize animals 

 with tuberculin, while most have succeeded with dead 

 bacilli and with aqueous extracts. This is not surprising; 

 indeed it is what should have been expected. Tuberculin 

 consists of digested, denatured proteins of relatively simple 

 composition. It is well known that peptones and poly- 

 peptids do not sensitize. The protein poison when detached 

 from other groups in the protein molecule sensitizes neither 

 to itself, nor to the unbroken protein. The fact that tuber- 

 culin does not sensitize or does so imperfectly raises a 

 serious question as to its employment as a therapeutic 

 agent. It is undoubtedly an excellent diagnostic agent 

 because its relatively simple structure may favor its prompt 

 cleavage when injected into an animal already sensitized 

 by the disease. But if it is not a sensitizer its therapeutic 

 good effect, if it has any such effect, must be confined to 

 the possible establishment of a tolerance to the tuberculo- 

 poison. Sensitization to tuberculoprotein can be induced 

 by bacillary emulsions, with watery extracts, and with 

 the non-poisonous residue. If the sensitization secured by 

 the last-mentioned agent is as good as that produced 

 by the others, it has the advantage of not containing any 

 poison. On the other hand, if the therapeutic effect desired 

 consists in the development of a tolerance to the poison, 

 tuberculin must be preferred unless we should use the more 

 completely isolated poison. 



1 Zeitsch. f. Immunitiitsforschung, 1913, xvii, 62. 



