no 



Scientific Proceedings (52). 



73 (769) 



On a new factor in passive anaphylaxis. 



By Richard Weil. 



[From the Department of Experimental Therapeutics, Cornell Uni- 

 versity Medical School, New York City.] 



After active sensitization guinea-pigs remain hyper-sensitive 

 for at least three years — probably for life. After passive sensitiza- 

 tion with homologous serum, i. e., with the blood of an immune 

 guinea-pig, they retain the sensitive condition so conferred for a 

 period of 60 or 70 days at least. After passive sensitization with 

 heterologous serum, i. e., with the blood of immune rabbits, they 

 lose the sensitive condition in 10 days or less. This rapid loss has 

 never been explained. It might theoretically be due to the devel- 

 opment by the injected guinea-pig of immune substances directed 

 against the introduced rabbit serum, which would then neutralize 

 or destroy the rabbit anti-bodies, on the presence of which sen- 

 sitization depends. This theory would explain the fact that the 

 injected guinea-pigs retain their sensitiveness for about ten days, 

 which would correspond to the time necessary to develop anti- 

 bodies. 



In order to test this idea, normal guinea-pigs were given a 

 subcutaneous injection of normal rabbit serum. After eight days 

 they were sensitized with a very large dose of the serum of a 

 rabbit immunized against horse serum, given intra-peritoneally. 

 Two days later, when tested by an intravenous injection of horse 

 serum, they failed to manifest any symptom of anaphylaxis. 

 The controls, although sensitized with a much smaller dose of 

 immune rabbit serum, and intoxicated with about one fiftieth 

 of the amount of horse serum used in the previous series, suc- 

 cumbed without exception. 



The refractory state towards passive sensitization, as thus 

 induced, may occasionally be demonstrated within three days of 

 the first injection. 



Partial immunization of guinea-pigs against rabbit antibodies 

 can sometimes be obtained by the previous injection of sheep 

 serum. It is, therefore, not strictly specific. 



