SIGNIFICANCE OF PHENOMENON 365 



reactions were obtained in the sites prepared; thus indicating 

 the possibility of producing reactions by the interaction of the 

 actively acquired anti-tuberculin antibodies with the tuberculin 

 injected, in tissues made reactive by the active principles. 



In another series of experiments there Avere obtained reactions 

 under conditions Avhich may be termed passi\e transfer. Rabbits 

 were prepared by intradermal injection of bacterial active prin- 

 ciples and following this, received an intravenous injection of 

 an anti-pneumococcus serum and inactive pneumococcus filtrate. 

 Strong reactions Avere then obtained at the prepared skin sites. 



Experiments remain to be done in order to determine the pos- 

 sible role of the active principles of this phenomenon in elicita- 

 tion of the Koch phenomenon and the "flare-up" reaction. 



Special consideration is also to be gi\en in the future inves- 

 tigations to the question of serum neutralization of reactions of 

 bacterial allergy. It has ])een shown in this monograph that 

 Avhilst the preparatory and reacting potencies of bacterial active 

 j)rinci])les may be neutralized specifically by immune sera, the 

 reacting jDotency of antigen-(-antibody complexes cannot be neu- 

 tralized. It is obvious, therefore, that in the reactions of bacterial 

 allergy neutralization may be expected only in those phases Avhen 

 the state of reactivity and the reactions are produced by the bac- 

 terial active principles, while no neutralization may be obtained 

 when the reactions are obtained through the interaction of the 

 injected antigen Avith antibodies acquired against the infection. 



Finally, experiments should also be done in order to determine 

 the connection of the facts presented to the problem on the rela- 

 tion of allergy to immunity. In the experiments described, anti- 

 bodies interacting with antigens may or may not contain neutral- 

 izing potency. Wlien the antibodies contain netitralizing potency 

 the antigen -)-antibody complexes are innocuous. When no neu- 

 tralizing potency is present in the antibodies the complexes may 

 become injurious if the ingredients occur in certain quantita- 

 tive relationships. Imminiity and allergy, therefore, mav represent 

 the same process, the fact whether the antigen-|-antibody com- 

 plexes are injurious or not may depend on the quantitative rela- 

 tionships Ijetween the two and also on the fact whether or not 

 neutralizing potency is associated with the antibodies. 



Since 1932 R. Kahn occupied himself with studies on necrotic 

 reactions folloAving injections of bacterial antigens into im- 



