An Experimental Study of Anti-anaphylaxis. i i 5 



tions. He concludes that anti-anaphylaxis presents a "most 

 interesting, novel, and as yet unexplained phenomenon." 



The following experiments appear to us to throw much light 

 on the problem. Guinea-pigs have been actively sensitized, by 

 injection, to a foreign proteid; after the lapse of about two weeks, 

 they have been rendered anti-anaphylactic by the intra-peritoneal 

 injection of a sublethal dose of this proteid. (That anti-ana- 

 phylaxis had actually been so induced was demonstrated by the 

 injection of relatively enormous doses of the proteid into controls 

 similarly treated, without toxic effect.) The anti-anaphylactic 

 animals have then been re-sensitized. This re-sensitization is ac- 

 complished by bleeding to death another guinea-pig, sensitized to 

 the identical proteid, and then injecting his serum, in amounts of 

 from 2 to 5^ cc -> hito the veins of the anti-anaphylactic animal. 

 After the lapse of less than 24 hours, the re-sensitized pig has been 

 tested by an intravenous injection of the foreign proteid. In each 

 and every case, the pig, upon undergoing this test, has manifested 

 the typical symptoms of anaphylaxis, with immediate death. In 

 other words, such a pig acts exactly like a normal pig, which has 

 been passively sensitized by the introduction of serum from an 

 anaphylactic pig. 



If instead of a sensitized pig, one makes use of the serum from 

 a pig highly immunized by means of repeated injections, re- 

 sensitization of the anti-anaphylactic animal is accomplished in 

 the same manner. 



If an actively anti-anaphylactic pig be passively re-sensitized 

 with the serum of a rabbit immunized to the same foreign proteid, 

 he too becomes hypersensitive, and is killed by a subsequent dose 

 of this proteid. 



The same experiments can be performed in the case of animals 

 rendered anti-anaphylactic after passive sensitization. If, during 

 the refractory period, say two days after the anti-anaphylactizing 

 dose, they are re-sensitized to the same foreign proteid by the 

 reintroduction of an immunized rabbit's serum, they may be killed 

 in the typical manner by the re-injection of the proteid. The only 

 difference between passive anaphylaxis as primarily and as 

 secondarily induced, is that in the latter somewhat larger doses 

 are required to re-sensitize. The cause of this difference is being 

 investigated and will form the subject of a later report. 



