382 Studies on Besredka Tuberculin [April-July. 



In another communication^ it was pointed out that whenever the 

 complement deviation with Besredka antigen is present in sera with 

 high hpotropic properties, it depends on the presence of a separate 

 tuberculous antibody possessing its own index different from the 

 hpotropic index of the same serum. It was found, moreover, that 

 the hpins which can be extracted from the tubercuhn with ether, 

 Chloroform, benzene or petroleum-ether are not sufficient, in the 

 quantity in which they are present in the tubercuhn, to cause a fixa- 

 tion of the complement in presence of hpotropic sera. 



Since the appearance of this publication, we have succeeded in 

 isolating the active pinciple of the tuberculin by means of precipi- 

 tation with ten volumes of absolute alcohol. Another efficient 

 method was the precipitation of protein from the tuberculin by 

 adding two drops of glacial acetic acid to 10 c.c. of Besredka 

 tuberculin which produced a heavy precipitate. This precipitate, 

 when centrifuged, suspended in 10 c.c. of physiological salt sol. 

 and neutralized to Phenolphthalein, proved to be an excellent antigen, 

 practically free from any lipin except the small amount adherent 

 to the precipitate. 



It was noticed, however, that different samples of antigen re- 

 ceived at different times from Professor Besredka's laboratory evi- 

 dently differed as to their antigenic value. How wide the ränge of 

 these differences in apparently similar samples of tuberculin was 

 found to be, is shown by the data in Table i. 



Whatever may be the cause of the comparatively low percentage 

 of positive reactions obtained, among cases of active tuberculosis, 

 with the antigen IV, the fact that the percentage of positive reac- 

 tions among syphilitics is so decidedly higher with it, suggested 

 the necessity of a renewed study of the role of the lipin fraction of 

 the tuberculin used in this series. The results of this study were 

 the following: Whereas, with products I and II, the amount of 

 lipin that could be extracted from the tuberculin by shaking with 

 different solvents was found to be too small to cause non-specific 

 lipptropic fixation; in the case of tuberculin IV, the amount of 

 lipin thus obtained was not only sufficient to explain the high per- 

 centage of positive reactions with syphilitic sera, but was almost 

 sufficient for use as antigen in the Wassermann reaction, as can be 



* J. Bronf enbrenner : Archives of Internal Medicine (in press). 



