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Scientific Proceedings (128) 



(Ph = 4.7) and in more acid and in more alkaline solutions. 

 With pure, crystallized hen ovalbumin (isoelectric point, P H = 

 4.8) we obtained anaphylaxis in the guinea pig readily and con- 

 sistently. When this protein is introduced into the animal in 

 solutions more acid than those in which it is isoelectric, it is a 

 distinctly more potent antigen than when introduced in the solu- 

 tion with which it is isoelectric or id more alkaline solutions. 

 Sensitization with 5 and intoxication with 50 milligrams of 

 ovalbumin gives acute and usually fatal anaphylaxis when the 

 sensitization is obtained with the protein at P H 2.0-2.5 regard- 

 less of the acidity of the intoxication dose. Sensitization with 

 the same dose of the protein at P H 4.7-4.8 or at 9.0-10.0, regard- 

 less of the form of the intoxicating dose, gives reactions which 

 range from only barely perceptible anaphylaxis to shock which 

 is evidenced by the usual paralysis but which is usually lacking 

 in the respiratory syndrome, the "air hunger," and which is prac- 

 tically never fatal. With larger sensitizing doses of protein (50 

 milligrams) acute anaphylaxis (including the respiratory as well 

 as the paralytic reaction) can be produced by the protein at any 

 of the three hydrogen-ion concentrations studied. We have ob- 

 tained entirely similar results in guinea pigs which were passively 

 sensitized with equal doses of the sera of rabbits, themselves ac- 

 tively sensitized with the acid, isoelectric and alkaline solutions 

 of ovalbumin. Further, we have obtained similar results by 

 the method of passive sensitization with a plant protein, the 

 crystalline globulin edestin (isoelectric point, P H = 6.9). Here 

 again the protein in acid solution is a more effective sensitizing 

 agent than in approximately isoelectric or in alkaline solution. 

 Its intoxicating potency apparently is not affected by the P H of 

 the solutions at the points tested (2.0-2.5; 6.2-7.0; 9.0-10.0). 



It is the tendency in immunological literature to stress the 

 parallelism between anaphylactic and precipitating antibodies in 

 immune sera. Indeed some workers incline to the view that the 

 two are identical (Coca, 3 1920). We have conducted some titra- 

 tions of precipitins in the rabbit sera which were used for the 

 passive sensitization of guinea pigs. With ovalbumin, the pre- 

 cipitin titrations were highest in the serum (anti-"acid antigen") 



3 Coca, A. F., 4 ' Hypersensitivenesa, " Tice's Practice of Medicine, pp. 

 107-198. 



