PART IV 



CHAPTER XXVIII 



ANAPHYLAXIS IN ITS RELATION TO INFECTION AND 



IMMUNITY 



IN reviewing our knowledge of the nature and mechanism of anaphy- 

 laxis we found that ordinarily innocent substances, such as sterile normal 

 serum and egg-albumen, when injected into animals, may give rise to 

 severe and even fatal intoxication, not because these substances are 

 poisonous in themselves, but because the antibodies which they stimu- 

 late the body-cells to produce react upon the innocent protein, causing 

 its cleavage, with the liberation of a harmful poison. Sere, indeed, we 

 have an example of antibodies apparently injuring our body-cells instead 

 of protecting them. And now the question very naturally arises, are 

 the lesions of the many diseases caused in a similar manner, the anti- 

 bodies splitting the bacterial cell and liberating the protein poison? In 

 view of the fact they may do actual harm, in some instances at least, are 

 antibodies really protective and beneficial, and if so, in what manner? 



It is not my purpose to review here the general subjects of infection 

 and immunity, but to discuss briefly the intimate and inseparable con- 

 nection of what we call anaphylaxis or allergy with infection, and to show 

 that anaphylaxis is really the first step in the process of immunity; 

 indeed, that well-marked antibacterial immunity is an example of an 

 early and efficient " anaphylactic " reaction. In other words, while the 

 striking and severe symptoms of serum anaphylaxis in either man or 

 lower animals give us the impression that we are here dealing with some 

 new, distinct, and strange phenomenon, these are, in fact, but exag- 

 gerated and severe examples, largely dependent upon quantitative 

 factors of what occurs during each infection. More than this, these 

 symptoms are due in part to the action of a poison formed or released 

 through the destruction of the antigen by the antibody; the antibody 

 being, therefore, apparently imperfect in its action, as it does not neu- 

 tralize the protein poison. Taking, as an example, a substance, such as 

 sterile horse serum; while ordinarily harmless itself, bad effects may 

 follow its injection at once if antibodies are present in our body-fluids, 

 or later if some of the serum persists in the body until antibodies are 



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