714 THE CHEMISTRY OF ANTIGENS 



As early as 191 2 Meyer' demonstrated specific complement-fixing antibodies 

 in the sera of animals immunized with lipoids derived from tubercle bacilli, though 

 he stated that these were much less antigenic than either the whole organisms or 

 those from which all lipoid had been extracted. Thiele and Embleton^ confirmed these 

 observations, demonstrating precipitins, complement-fixing and anaphylactic anti- 

 bodies in sera obtained by injecting phosphatides obtained from tubercle bacilli. 

 Long and Seibert^ have separated three distinct proteins from filtrates of cultures 

 of the tubercle bacillus, all of which showed tuberculin activity, though their true 

 antigenic properties were not tested. Zinsser and Tamiya" have separated two distinct 

 active fractions from the tubercle bacillus: so-called "nucleoproteins" which cause 

 antibody production, and are species specific but not type specific; and a part which 

 reacts with striking type specificity in the presence of antiserum, but which does not 

 incite antibody formation in animals. This latter fraction, designated by Zinsser as 

 "residue antigen," has been found by Mueller^ and by Laidlaw and Dudley^ to consist 

 chiefly of a gum. Dienes and Freund^ have described three specific fractions in the 

 tubercle bacillus: (i) a protein, (2) a lipin, and (3) a complex carbohydrate. The first 

 two they report to be truly antigenic in that they induce antibody formation; the 

 carbohydrate is specifically precipitable by antisera, but is not truly antigenic. 



Similar studies have been made of other bacteria. The careful studies of Avery 

 and Heidelberger^ with the fixed types of pneumococci demonstrated the presence 

 in these of a common protein, species specific and truly antigenic; and in each type 

 a distinctly characteristic carbohydrate, highly specific for its own type alone but 

 incapable of inciting antibody formation. 



My own study of the antigens found in filtrates of cultures of some members of 

 the paratyphoid group of bacteria grown in a synthetic medium has resulted in the 

 separation of similar fractions: one, containing at least 9 per cent of nitrogen and 

 giving all of the usual protein reactions, which is specific and truly antigenic; and 

 the other, a stable complex carbohydrate definitely precipitable with antisera.' 



Little has been done on the number and types of proteins found in bacterial cells. 

 Nelson'" has found the globulins in the colon-typhoid group to be antigenic, their 

 specificity within the group being strikingly quantitative. 



•Meyer, K.: Ztschr.f. Immunitatsforsch. u. exper. Therap., 15, 245. 1912. 



^Thiele, F. H., and Embleton, D.: J. Path. &" Bad., 19, 349. 1915. 



3 Long, E. R., and Seibert, F. B.: J. A.M. A., 85, 650. 1925. 



^Zinsser, H., and Tamiya, T.: J. E.rper. Med., 42, 311. 1925; Zinsser, H., and Parker, J.: ibid., 

 37, 275. 1923. 



s Mueller, J. H.: ibid., 43, i and 9. 1926. 



'Laidlaw, P. P., and Dudley, H. W.: Brit. J. Exper. Path., 6, 197. 1925. 



'Dienes, L., and Freund, J.: /. Immunol., 12, 137. 1926. 



* Avery, O. T., and Heidelberger, M.: /. Exper. Med., 38, 81. 1923; 42, 367. 1925; Heidelberger, 

 M., and Avery, O. T.: ibid., 38, 73. 1923; 40, 301. 1924; Heidelberger, M., Goebel, W. F., and 

 Avery, O. T.: ibid., 42, 727. 1925; Heidelberger, M.: Chem. Rev., 3, 403. 1927; cf. chap, lii in this 

 volume. 



' Branham, S. E. : unpublished work. 

 "Nelson, C. I.: J. Inject. Dis., 38, 371. 1926; 40, 412. 1927. 



