CHAPTER XIX 



BACTERIAL ANTIGENS AND SPECIFICITY 



Bacterial Antigens. — Complexity. — Landsteiner (1936), Wells 

 (1929), Zinsser (1928, 1939), and others have called attention to 

 the complexity of cellular or protoplasmic antigens as contrasted 

 with isolated and purified proteins. While species specificity can, 

 as a rule, be demonstrated for intact red blood cells by means of 

 high-titered immune serum, one frequently encounters difficulty 

 in determining bacterial species by agglutination, absorption, and 

 complement fixation. 



Living Attenuated Antigens. — Interest in bacterial antigens 

 began Avith the immunization experiments of Pasteur. He found 

 that attenuated, living cultures Avere efficient vaccines for protec- 

 tive inoculation. Since that time the French scliool has continued 

 to regard suspensions of living attenuated bacteria as the most 

 desirable immunizing agents. 



Killed Suspensions as Antigens.- — Widal (1896), Bordet, 

 Gruber and Durham and others who initiated the serological 

 identification of bacteria by agglutination, noted that dead sus- 

 pensions of E. tupliosa or Vibrio comma were quite satisfac- 

 tory antigens. Later work by Felix and Pitt (1934) and others 

 has shown the importance of labile antigenic factors in agglutina- 

 tion reactions. 



Early Research on Antigens. — From Pick's (1908) review of 

 the early literature it is evident that there were carried out exten- 

 sive investigations of the effect of physical and chemical agents 

 on the antigenic property of bacteria. He calls attention to tlie 

 early use of heat-killed suspensions as well as to the use of phenol, 

 formalin and other chemicals for the preservation of antigens or 

 as germicidal agents. 



Species Specificity vs. Immunological Specificity. — Interest in 

 the relationship between species specificity and immunological 

 specificity developed early. In 1902 Castellani introduced the 

 absorption technique. There soon developed among many bac- 

 teriologists a belief that by the use of agglutination and absorption 



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