HYPERSENSITIVENESS, PROTEIN INTOXICATION 217 



increase or decrease susceptibility is for the most part unknown, but 

 from a theoretical as well as a practical standpoint, considerable impor- 

 tance is attached to the procedures which alter in either direction the sus- 

 ceptibility of the sensitized animal to reinjection. 



Whatever be. its mode of action, the fact has been demonstrated that 

 if quinin be injected before the intoxicating dose of antigen, the minimal 

 lethal dose is reduced and the symptoms from. a sublethal dose are more 

 severe than in control animals untreated with quinin. Smith (a) has also 

 shown that histamin exerts a synergic action when administered just 

 before the. reinjection. 



On the other hand, there are numerous substances to which has been 

 attributed the property of partially or completely protecting a. sensitized 

 animal against the intoxicating dose. Friedberger and Hartoch showed 

 that guinea-pigs may be partially protected by 1 c.c. of a saturated solu- 

 tion of sodium chlorid injected intravenously before the antigen is given. 

 Richet and his collaborators have also protected dogs by intravenous in- 

 jections of sodium chlorid solutions. Biedl and Kraus, as mentioned 

 above, obtained in dog,s a non-specific anti-anaphylaxis by injecting in- 

 travenously 0.25 to 0.5 gm. of peptone per kilo of body weight, though 

 Besredka was unable to show that anaphylatoxin had a similar effect 

 in guinea-pigs and one of us has confirmed these results with histamin. 

 Barium chlorid, urethan, chloral hydrate (Auer) and methyl guanidin 

 have all been credited with the property of rendering animals less sus- 

 ceptible to the anaphylactic injection. Ether narcosis was recommended 

 by Besredka as a procedure which lowers the mortality of reinjected guinea- 

 pigs by lessening the irritability of .the bronchial musculature. Auer(a) 

 found that the intravenous or subcutaneous injection of atropin pro- 

 tects 70 per cent of sensitized guinea-pigs against the minimal lethal 

 dose of antigen. Adrenalin, by sympathetic stimulation relaxes the 

 bronchial musculature and in this way lessens the severity of the ana- 

 phylactic reaction in those animals in which bronchial spasm is an im- 

 portant factor. In man, its effect is marked, though fleeting, in anaphy- 

 lactic reactions characterized by respiratory difficulty and urticaria. So- 

 dium oleate has been found by Kopoczwski and Vakram to suppress the 

 symptoms of guinea-pig anaphylaxis. They attribute its effect to a re- 

 duction of plasma surface tension, and found that other substances such 

 as saponin, sodium taurocholat and sodium glycocholat, which also re- 

 duce surface tension have a similar prophylactic effect upon animals sub- 

 jected to reinjection of the antigen. 



An interesting type of interference with sensitization has been de- 

 scribed by Julian Lewis who found that when comparatively large quan- 

 tities of a protein different from that employed for sensitization were in- 

 jected simultaneously with the dose of sensitizing protein, or shortly 



