RELATION OF ANAPHYLAXIS TO INFECTIOUS DISEASES 603 



if antibodies are present in our body-fluids, or later if some of the serum 

 persists in the body until antibodies are produced. It would appear, 

 therefore, that when the antibodies are produced for a given infectious 

 agent, then the severity of the disease becomes apparent ; that the lesions 

 and symptoms are due not only to the infecting microorganism and its 

 products, but to the results of their destruction. An invading army 

 may do some pillaging, but the greatest injury is done when the de- 

 fenders begin the attack, the resulting fire and destruction doing more 

 harm than the invaders themselves. 



While Vaughan and his coworkers were studying the protein poison 

 in vitro, and Friedberger was investigating it in vivo, the former and then 

 the latter aiming to show that the poison liberated from the protein 

 molecule through the action of specific ferments is responsible for the 

 lesions and symptoms of disease, von Pirquet was studying the question 

 from the clinical aspect, formulating a working hypothesis on the nature 

 of infection and immunity based upon the principles of anaphylaxis, a 

 theory that has been supported by experimental data and has thrown a 

 new light upon the nature and mechanism of these processes. 



RELATION OF ANAPHYLAXIS TO INFECTIOUS DISEASES 

 Although we may not be in general accord regarding the mechanism 

 of anaphylaxis, if the humoral theory is accepted there is a general 

 agreement as regards the nature of the anaphylatoxin responsible for 

 the lesions and symptoms of anaphylactic intoxication, namely, that 

 it is a protein cleavage product. In other words, a foreign protein and, 

 indeed, the misplaced protein of our own body-cells may be disrupted 

 or digested by an antibody, and liberate or generate a poison that, 

 being derived from protein, is known as the protein poison. In the 

 chapter on Infection it was stated that Vaughan and his collaborators 

 regard this protein poison as the same for all proteins, and as responsible 

 for all infectious diseases, the particular lesions and symptoms of each 

 disease being dependent upon the site of the infection and, accordingly, 

 upon the location of the protein poison. Similarly, in the preceding 

 chapter we asserted that anaphylaxis may be ascribed to an exactly 

 similar phenomenon, namely, the splitting of the foreign protein by an 

 antibody (ferment) and the liberation of a protein poison. In studying 

 serum sickness, an anaphylactic phenomenon frequently observed in 

 man following the administration of horse serum, von Pirquet argued 

 that the period of from eight to ten days usually following the injection 



