3^4 Studies on Besredka Tuherculin [April-July. 



It was found that, when concentrated many times, the emulsion 

 of lipins from tuberculin II was also able to fix the complement with 

 syphilitic sera but, in the amount in which it was present in the 

 tuberculin (Table 2), it was not sufficient to cause the non-specific 

 fixation. 



If we seek causes that account for the evident differences in 

 apparently similar samples of Besredka tuberculin, several possible 

 answers suggest themselves. (i) Since the tuberculin consists of 

 the culture media in which tubercle bacilli have grown for a cer- 

 tain length of time (and there necessarily exist a number of possi- 

 ble variations affecting the rate of growth of different lots of cul- 

 tures), different cultures are likely to contain variable amounts of 

 the metabolic products of the organism. (2) A further source of 

 Variation lies in the fact that, in the process of preparation, tuber- 

 culin is heated under pressure to kill the tubercle bacilli and some 

 unrecorded variations in the heating process might cause destruc- 

 tion of the antigenic value of the protein fraction of the tuberculin. 



(3) Moreover, it followed from our comparison of different tuber- 

 culins^ used as antigens in the complement-deviation test, that in 

 tuberculosis (as well as in other diseases), there exists a certain 

 variability of specificity with different strains of tubercle bacilli, 

 which probably necessitates in turn the preparation of a polyvalent 

 antigen containing not only several human but also bovine strains. 



(4) The fact that the composition of Besredka tuberculins, in refer- 

 ence to the number of strains and respective amounts of each in 

 given tuberculin preparations, might differ, would also account, 

 possibly, for the observed variations in the antigenic value of the 

 tuberculins. (5) Lastly, variations in the amounts of tgg yolk, 

 which is the primary source of the lipins in the antigen, probably 

 affect the chemical qualities of the medium, of which the tuberculin 

 is mainly composed. 



Whatever the reasons for the differences may be, the very pos- 

 sibility of such variations suggested the necessity of standardizing 

 the antigen in some way so as to insure uniform results with any 



ß We take this opportunity to thank most sincerely Prof. W. H. Park of the 

 N. Y. Board of Health, as well as Dr. E. M. Houghton of Parke, Davis and Co., 

 and Dr. A. P. Hitchens of Mulford Company, who kindly added different prep- 

 arations of their tuberculins to our own series. 



