402 IMMUNO-CATALYSIS 



Acute anaphylactic death in the rabbit is due to a spasmodic con- 

 striction of the pulmonary artery, followed by rapid dilatation of the 

 right side of the heart which is the most characteristic abnormality in 

 this animal (Coca, 1919). 



Various observations have indicated that there exists a consistent 

 similarity between the circulatory reactions in the anaphylactic rabbit 

 and the pharmacological effects of histamine (Dale and Laidlaw, 1910- 

 11; Rocha e Silva, 1940). Katz (1940) observed that when antigen is 

 added to the blood of a sensitized rabbit in vitro, there is a striking shift 

 of histamine from corpuscular elements to the plasma. This observation 

 has been confirmed (Dragstedt, Ramirez and Lawton, 1940; Rose and 

 Browne, 1941).* The relation of these observations to anaphylaxis in 

 the rabbit has been critically discussed by Rose (1947) who would 

 seem to agree with Dragstedt (1945) that the fundamental phenom- 

 enon in rabbit anaphylaxis is a liberation of histamine from cells into 

 the plasma. 



In any species, additional symptoms in anaphylaxis are aggregation 

 of polymorphonuclear cells in the capillaries of the lungs to produce 

 a leucopenia, a decrease in coagulability of the blood, most marked in 

 the dog, a decrease in the amount of complement in the blood, and a 

 fall in the body temperature. In anaphylaxis the following chemical 

 changes have been observed. There is loss of histamine from cells into 

 the plasma, histamine-like substances are liberated, serum potassium 

 increases, plasma suffers lowering of carbon dioxide combining, or 

 alkali reserve capacity, or there is an immediate and progressive acidosis. 

 Acidosis appears before the onset of recognizable clinical symptoms of 

 shock. There is also an increased secretion of urinary creatine, uric 

 acid and urea ammonia, indicating derangement in liver function and 

 protein metabolism. These changes will be further discussed below 

 in relation to the biochemical mechanism of shock. 



2. Peptone Shock 



The shock produced by the injection of peptone resembles true 

 anaphylactic shock in many respects. Contraction of the bronchioles 

 in the guinea pig, fall of blood pressure and congestion of the liver in 



*See, however, discussion on page 438. 



