CHAPTER LXXVI 

 TUBERCULIN AND THE TUBERCULIN REACTION 



ESMOND R. LONG 

 University of Chicago 



DEFINITION OF TUBERCULIN AND THE TUBERCULIN REACTION 



In 1 89 1 Robert Koch^ announced his discovery of a specific reaction occurring on 

 the introduction of extracts or other products of the tubercle bacillus into the bodies 

 of tuberculous animals. Whole or disintegrated dead bacilli, aqueous and glycerol ex- 

 tracts of them, protein precipitates from such extracts, and the culture medium on 

 which the bacillus had grown, were all effective in producing the reaction. Normal 

 animals failed to respond to the introduction of this material. The tuberculous, on 

 the other hand, reacted locally, focally, and generally, i.e., an acute inflammation 

 developed at the locus of injection, and around all active foci of disease, while the 

 animal exhibited signs of general intoxication with rise in temperature. 



The substances eliciting the reaction were grouped under the name "tuberculin," 

 and the specific reaction was designated the "tuberculin reaction." Noting that the 

 tuberculin reaction occurring on the introduction of dead or living tubercle bacilli 

 into the skin of a tuberculous animal led to necrosis with sloughing of the tissue in- 

 oculated with bacilli, Koch developed immunological concepts of the tuberculin reac- 

 tion and introduced tuberculin as a specific therapeutic agent against tuberculosis. 



PREPARATIONS USED AND THEIR STANDARDIZATION 



Koch believed a specific active principle was present in all his tuberculin prepara- 

 tions, and made a well-directed effort to isolate it, which will be described below. He 

 advocated two of his many preparations as particularly suitable for therapy. These 

 were his A T (Alt Tuber kulin) , or in English O T (Old Tuberculin), and B E^ {Bacillen 

 Emulsion ["bacillary emulsion"]; new tuberculin). Since Koch's time an enormous 

 number of tuberculin preparations have been described or put on the market. Bald- 

 win, Petroff, and Gardner^ list over a hundred such tuberculins and allied products. 

 Of all of these, Koch's Old Tuberculin has been used most extensively. This consists 

 of glycerol bouillon on which the tubercle bacillus has been cultivated, freed from the 

 baciUi by filtration after one hour's boiling of the whole culture, and evaporated to 

 one-tenth of its original volume. His B E consists of a glycerol and water suspension 

 of dried and finely ground bacilli. Both preparations are diluted with salt solution 

 before use. 



Koch himself recognized the need for some sort of standardization of these prod- 



'Koch, R.: Deutsche mcd. Wchnschr., 17, loi. 1891. 

 ^ Koch, R.: ibid., 27, 829. 1901. 



3 Baldwin, E. R., Petroff, S. A., and Gardner, L. U.: Tuberculosis. Bacteriology, Pathology, and 

 Laboratory Diagnosis. Philadelphia, 1927. 



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