598 ANAPHYLAXIS 



antibody during the latent period, and that anaphylaxis is the result 

 of an interaction between the cellular antibodies and the antigen. 



It would appear that passive anaphylaxis is not wholly determined 

 by the amounts of antigen or antibody, but by the proportion that 

 exists between the two. For example, Friedmann, 1 in his studies on 

 passive homologous anaphylaxis in rabbits, found that, by employing 

 2.5 c.c. of antiserum with from 2.5 to 0.25 c.c. of antigen, no results were 

 observed, whereas positive reactions were obtained when the amount of 

 antigen was reduced from 0.025 to 0.0025 c.c. 



Ordinarily, normal guinea-pigs may be passively sensitized by 0.1 to 

 0.5 c.c. of serum injected intraperitoneally, and anaphylactized one or 

 two days later by an intravenous injection (0.1 to 0.5 c.c.) of the antigen. 

 The immune serum may be prepared by injecting rabbits with horse 

 serum, after the methods for the production of precipitins described in 

 Chapter IV. 



The duration of passive sensitization is quite variable. Weil 2 found 

 that guinea-pigs sensitized with a homologous serum, that is, with the 

 serum of another guinea-pig sensitized with horse serum, remain typic- 

 ally anaphylactic as long as seventy days after the injection. With 

 heterologous sensitization, however, as with the serum of a sensitized 

 rabbit, hypersensitiveness is almost invariably lost by the tenth day. 

 One explanation of this would be that a heterologous serum is excreted 

 more rapidly than a homologous serum, a condition commonly observed 

 in serum therapy with any heterologous serum. 



The Mechanism of Passive Anaphylaxis. Presumably the mecha- 

 nism of passive anaphylaxis in terms of the humoral theory is relatively 

 simple, and consists in the transfer of the specific protein sensitizer or 

 amboceptor that unites the anaphylactogen or protein antigen with a 

 complement, bringing about lysis or cleavage of the protein and liber- 

 ation of the toxic moiety responsible for the lesions and symptoms of 

 anaphylaxis. In other words, the mechanism of passive anaphylaxis 

 may be likened to passive antibacterial immunization, with, however, 

 one important clinical difference, namely, that whereas in the former 

 the microorganisms are destroyed without apparent injury to the 

 host, in anaphylaxis the body-cells are acutely poisoned. However, a 

 similar phenomenon in the serum treatment of disease, with lysis of 

 bacteria, may be overshadowed or possibly prevented by a condition 

 t of anti-anaphylaxis. 



According to the cellular theory, passive anaphylaxis is due to the 



1 Jahr. u. d. Ergeb. Immunitatsf., 1910, vi, 67. 



2 Jour. Med. Research, 1913, 28, No. 2, 359. 



