618 ANAPHYLAXIS IN RELATION TO INFECTION AND IMMUNITY 



placental protein, as in Abderhalden's pregnancy reaction, is rendered 

 totally inactive by heating the serum. Others ^believe that heating 

 diminishes the activity of the ferment, but does not destroy it altogether; 

 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 acts with the protein substance, which may be either a harm- 

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

 production of anaphylaxis; second, a state of hypersensitiveness of the 

 body-cells. 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 recog- 

 nize a peculiar hypersensitiveness of these cells, due probably to the 

 fact that protein amboceptors 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 apparently related 

 with that concerned in antibacterial immunity. Vaughan believes that 

 the same mechanism is identical in all forms of immunity, but we can- 

 not subscribe to this view because the mechanism concerned in anaph}^- 

 laxis 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 antibacterial immunity, however, where the chief action lies in digest- 

 ing the infecting cells, the mechanism may be regarded as similar with 

 that concerned in producing the anaphylatoxin or protein poison of the 

 humoral theory. The effects 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, 



