580 ANAPHYLAXIS IN RELATION TO INFECTION AND IMMUNITY 



the point cannot be decided at present, mainly because of technical 

 difficulties, but, for the sake of simplicity at least, we may regard the 

 protein-splitting ferments as quite similar to the cytolysins; indeed, 

 they may be identical. 



In anaphylaxis we recognize two primary factors: first, the anti- 

 body, which splits the protein substance, which may be either a harmless 

 sterile protein, such as horse serum or pathogenic bacteria, with the 

 liberation of a protein poison which intoxicates body-cells; second, a 

 state of hypersensitiveness of the body-cells to this poison. While it is 

 clearly apparent that the protein poison generated in the test-tube may 

 intoxicate normal animals with the first injection, yet to understand the 

 extreme sensitiveness of body-cells in persons susceptible to horse 

 protein, where, for example, a few inspirations of stable air are sufficient 

 to bring on an attack of asthma, we must recognize a peculiar hyper- 

 sensitiveness of these cells, due probably to the fact that protein ambo- 

 ceptors are attached to the cells and unite with the inhaled protein with 

 great avidity. , ' 



The relation of anaphylaxis to immunity consists, therefore, in the 

 fact that the mechanism concerned in anaphylaxis is identical with that 

 concerned in antibacterial immunity. Vaughan believes that the same 

 mechanism is identical in all forms of immunity, but we cannot sub- 

 scribe to this view, because the mechanism concerned in anaphylaxis 

 does not explain antitoxin immunity, or at least the antibodies concerned 

 in neutralizing diphtheria toxin are different from those digesting or 

 splitting a bacterial protein, as, for example, typhoid bacilli. In anti- 

 bacterial immunity, however, where the chief action lies in digesting the 

 infecting cells, the mechanism may be regarded as identical with that 

 concerned in producing the anaphylatoxin or protein poison. The ef- 

 fects are, however, different. In infection we have the combined 

 action of toxins, endotoxins, and protein poison upon the body-cells; 

 in serum anaphylaxis we have the effects of the protein poison alone. 

 Lesions and symptoms of disease, therefore, may be regarded as the 

 summation of the products of infection and anaphylaxis. 



When we inject a bacterial vaccine we inject so much bacterial pro- 

 tein. This protein sensitizes body-cells and causes them to produce an 

 amboceptor (sensitizer or the anaphylactic ferment); this antibody 

 serves to bring about death by lysis of any corresponding bacteria in the 

 body (therapeutic immunization), or of any that may subsequently 

 gain access (prophylactic immunization). The effects, if apparent, 



