BACTERIAL ANTIGENS AND SPECIFICITY 355 



Antigenic Comparisons of Acid-Fast Bacteria. — Lewis and 

 Seibert* (1931, 1933) have made extensive antigenic comparisons 

 of different strains of the tubercle bacillus and the timothy 

 bacillus. They found definite antigenic relationships and also 

 differences between the human, bovine and avian strains but 

 only slight relationship between any of these and the timothy 

 bacillus. 



It has been shown that tubercle bacilli contain lipoids, pro- 

 teins and carbohydrates. The question as to the immunological 

 importance of each of these has led to much controversy. All 

 three types of substances have been reported as giving serological 

 reactions. 



They conclude that, "The sensitized animal body is able to 

 make a quantitative distinction between the proteins from dif- 

 ferent types of acid-fast bacilli, but is apparently unable to dif- 

 ferentiate the proteins from different strains of the same type, 

 such as between virulent and avirulent organisms." 



Lipoids. — In regard to the lipoids. Wells (1929) calls attention 

 to the possibility that perhaps many of the lipoid preparations 

 that have been studied contain a trace of protein. He considers 

 that alcohol-soluble proteins may be present in bacterial extracts 

 and that their presence might account for the results of Klop- 

 stock and Witebsky (1927) who found that alcoholic extracts of 

 bacteria were antigenic and Pinner (1927, 1928) who noted an 

 increase in the antigenic property of alcoholic extracts of tubercle 

 bacilli as the protein content was diminished by purification. 



Relative Importance of Lipoids, Proteins and Carbohy- 

 drates. — There seems to be fairly good evidence indicating that 

 the lipoid fraction of the tubercle bacilli is similar for all strains 

 and that it does not determine serological specificity. On the other 

 hand, the protein fraction, containing carbohydrate configurations, 

 is quite specific. Long (1930) considers that the polysaccharides 

 of the tubercle bacillus are immunologically specific as shown by 

 Laidlaw and Dudley (1926), Mueller (1926) and Zinsser and 

 Tamiya (1925), His conclusions" are apparently confirmed by 

 the later work of Seibert, Pedersen and Tiselius (1938) and Heidel- 

 berger and Menzel (1938). 



♦Lewis, J. H., and Seibert, F. B. : J. Immunol. 20: 201, 1931. 



