362 



INFECTION AND IMMUNITY 



whether it takes any important part in the phenomena is at present 

 a matter of considerable doubt. 



We can feel safe, therefore, in stating very definitely that the 

 site of the anaphylactic reaction, that is, the place at which the 

 union between antigen and antibody occurs in the production of 

 the various symptoms of anaphylactic injury is upon the cells. That, 

 in other words, the important reaction which determines the train 

 of symptoms which we call anaphylaxis occurs when the antigen 

 goes into relationship with antibodies which are still in some way 

 united to tissue cells, or are, in the jargon of immunology, "sessile" 

 upon the cells. 



Whether or not any injury may occur when antigen meets anti- 

 body in the circulation is still an open question. There are experi- 

 ments on record by Friedemann 40 in wliich he obtained reactions 

 in rabbits by the simultaneous intravenous injection of antigen and 

 antibody, and similar occasional occurrences have been observed 

 by Brion, Scott and ourselves. But these reactions are neither 

 regular in occurrence, nor are they ever very severe. As a matter 

 of fact, as we have shown, the union of antigen and antibody in 

 the circulation is inhibited probably by colloidal protection, and 

 this may be regarded as being very likely a protective mechanism. 

 As a matter of fact, Weil and others have shown that a sufficient 

 amount of antibody in the circulation may even protect the cells 

 to some extent against anaphylactic shock, and it is interesting 

 to note in this connection that very large doses of protective anti- 

 serum are necessary to bring about this result, a circumstance which 

 is again easily explained by the inhibition of union between cir- 

 culating antigen and antibody. 



Concerning the possibility of the formation of poisonous sub- 

 stances in the circulation, produced by the union of antigen-anti- 

 body, a question which is involved in Friedberger's theory of 

 anaphylaxis, we will have more to say in a subsequent paragraph. 



SYMPTOMS OF ANAPHYLAXIS. Anaphylaxis differs in its symp- 

 tomatology and pathology according to the species of animal in 

 which shock is produced. There are certain fundamental systemic 

 reactions which are common to all species, but in each species that 

 has been observed, there are particular localization of the immediate 

 and severe changes which lead to acute death. As general symptoms 



40 Friedemann, Zeit. f. Immunit., 2, 1909. 



