528 IMMUNOLOGY 



sively sensitized to egg albumen, they invariably observed the 

 anaphylactic type of response. 



Histological studies of the various skin reactions confirmed the 

 gross findings. The anaphylactic reaction in passively sensitized 

 guinea pigs is characterized by an immediate serous and poly- 

 morphonuclear exudate. In guinea pigs actively sensitized to egg 

 albumen and tested on the sixth day the reaction is delayed. It 

 appears in about six hours and persists forty-eight hours or longer. 

 Microscopically the cellular reaction is predominantly mononuclear. 

 When the actively sensitized pigs are tested on the eighth day 

 or later the reaction is immediate and the cellular exudate contains 

 a predominance of polymorphonuclear cells. 



Similarity Between Immune Response and Tuberculin 

 Allergy. — The authors believe that the ratio of mononuclear to 

 polymorphonuclear cells is a valuable criterion of differentiation 

 between the two types of hypersensitiveness. They conclude that 

 the tuberculin type of hypersensitiveness represents the first stage 

 of the immune response to the introduction of any antigen within 

 the tissues of a suitable animal. In tuberculous animals there 

 is a fixation of this early stage for tuberculin protein so that skin 

 reactions to tuberculin are always of the tuberculin type. In 

 protein anaphylaxis, on the other hand, there is no fixation of the 

 early stage, but, instead, the anaphylactic type supervenes after 

 the sixth day. 



The observation of Dienes that the injection of egg albumen 

 and other protein antigens directly into a lesion causes in some 

 manner subsequent skin reactions to the homologous antigen to 

 be of the tuberculin type, whereas antigen injected elsewhere 

 leads to the anaph.ylactic type of reaction, may be explained in 

 part at least on the basis of the time factor. 



If the egg albumen is injected directly into a lesion, its aljsorp- 

 tion may be delayed and the primary stage of tlie immune re- 

 sponse therefore prolonged. Dienes' work suggests that dosage 

 and other factors as yet unknown are involved. In his experi- 

 ments where sensitizing injections of egg albumen were made 

 away from the lesion it is interesting to note that skin tests were 

 never done as early as the sixth day, hence the early stage typical 

 of the tuberculin type of allergy was not detected. A careful 

 reading of Dienes' papers reveals many exceptions and also nu- 



