HOST RESPONSE TO ANTIGENIC ACTION 447 



dermal tissues of animals thus treated display a newly established 

 function when brought into contact with these products. Actively 

 acquired hypersensitivity may be duplicated by the injection of 

 normal animals with some forms of antipneumococcic serum. 



The interaction between specific immune serum and the pneumo- 

 coccal cell resulting in the formation of a substance capable of 

 eliciting acute anaphylactic shock in the guinea pig was first 

 demonstrated by Neufeld and Dold (1911 ). 981 Cocci sensitized 

 with homologous antiserum and injected into guinea pigs regu- 

 larly caused the acute death of the animals. The effect was as- 

 cribed by Neufeld and Dold to the production of anaphylatoxin. 



ACTIVELY INDUCED SENSITIZATION 



In 1911, Rosenow 1165 claimed that, by the subcutaneous, intra- 

 venous, intrapleural, and intraperitoneal injection of killed pneu- 

 mococci or of filtered pneumococcal extracts into guinea pigs, he 

 could so sensitize the animals that they responded with severe in- 

 toxication when the same bacterial extract was injected eight to 

 twelve days later into a vein or into the heart. In a subsequent 

 study, Rosenow (1912) 1166 was able to obtain highly toxic sub- 

 stances from Pneumococcus through autolysis, from Pneumococ- 

 cus-leucocyte mixtures, and by the action of normal and of im- 

 mune serum on the organisms. These toxic substances evoked in 

 normal guinea pigs symptoms indistinguishable from the symp- 

 toms of immediate anaphylaxis. The action of the poisonous sub- 

 stances as well as of the preparations of Cole, Weiss, and others 

 has been discussed in Chapter III, and undoubtedly is to be at- 

 tributed to histamine-like protein-degradation products. 



Clough (1915) 241 employed saline extracts of washed, dried, and 

 ground pneumococci as sensitizing antigens and as the intoxicat- 

 ing agent. The extracts so prepared were sufficiently toxic to cause 

 anaphylactoid reactions in normal guinea pigs. However, by pre- 

 cipitating the extracts with alcohol, Clough isolated a substance, 



