400 IMMUNO-CATALYSIS 



man, such as hay fever, pollen asthma, atopic urticaria, and perhaps 

 others are based upon similar mechanisms. In all these cases, antibodies 

 are formed which unite with the antigen and in each case it is the 

 union of antigen and specific antibody followed by cell injury which 

 produces the allergic symptoms. 



It is generally accepted that the antigen unites with antibody which 

 is fixed to cells. Exemplified by anaphylaxis, explosive and violent in 

 character, with marked effects on the respiratory, circulatory, glandular 

 and smooth muscle systems, this reaction is a fundamental and chal- 

 lenging biochemical problem in immunology whose specific mechanism 

 awaits elucidation. Undoubtedly cell injury occurs during the antigen- 

 antibody reaction. As a consequence, or associated with the antigen- 

 antibody reaction, in addition to histamine, several physiologically 

 active substances, such as heparin, possibly choline or acetyl-choline, 

 potassium, glucose and various enzymes are let loose. Asphyxia as- 

 sociated with all types of shock plays an important role in cell-injury 

 and cellular disorganization. In connection with the view that it is 

 not the free or circulating antibodies, but those attached to the fixed 

 tissue cells which are most concerned with this reaction, Moon (1938) 

 cited the following: (a) the incubation of antibody with antigen in 

 vitro does not produce a potent injurious product; (b) antigen-antibody 

 precipitate is relatively innocuous; (c) antibody and antigen simultane- 

 ously injected fail to produce shock in nonsensitized animals; (d) in 

 passive sensitization an interval of several hours must elapse before the 

 injection of antigen produces shock symptoms; (e) if the blood from 

 a sensitized animal is replaced by blood from normal animals of the 

 same species, the animal still remained sensitive; and (f ) organs whose 

 vessels had been washed clean of blood by perfusion with salt solution 

 still responded characteristically to the antigen. 



The dominant symptoms of bronchiospasm in the guinea pig, of 

 circulatory failure in the dog, and cardiocirculatory failure in the 

 rabbit could all be harmonized on the basis of a spastic contraction 

 of strategically located smooth muscle. The critical site of activity for 

 this reaction is the smooth muscle in the bronchioles of the guinea 

 pig, the hepatic veins of the dog, and the pulmonary arterioles of the 

 rabbit. These considerations demonstrate that the fundamental reac- 

 tion in all animals is probably identical (Simonds, 1919; Drag- 

 stedt, 1941). Sufficient histamine is claimed to be liberated during 



