Serological Studies of Diphtheria Group. 



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109 (1856) 



Serological studies of the diphtheria group. 



By CARL O. LATHROP and CHARLES A. BENTZ. 



[From the Bacteriological Laboratories of the Medical Department, 

 University of Buffalo, and Buffalo Bureau of Laboratories, 

 Buffalo, N. Y.] 



A systematic qualitative and quantitative study has been 

 made on the immunity developed in a group of young adults 

 immunized against diphtheria with toxin-antitoxin. 



As a preliminary, a successful attempt was made to corroborate 

 Havens' contention that there are two serological groups of diph- 

 theria bacilli with specific agglutinogenic properties and no 

 evidence of cross agglutination. For our minor group antigen 

 we used two cultures recovered from cases of diphtheria developed 

 in persons immunized with toxin-antitoxin and yielding negative 

 Schick tests. 



This specificity has been further substantiated by antibody 

 absorption, which confirms the other findings completely. 



Incidentally, we used rabbit blood agar plates exclusively for 

 isolation and study of the organisms, and noted that hemolysis, 

 a sometime mooted point, is not characteristically allied with 

 virulence, nor does it only occur in freshly isolated cultures, but 

 may crop up as late as the 56th generation. 



We have also found, as we believe Park stated, that certain 

 true diphtheria bacilli possess a factor of virulence not neutralized 

 by antitoxin, concerning whose identity we are making a further 

 study. Likewise we have confirmed Park and Havens in finding 

 that there is some group antitoxin present in the antitoxin com- 

 monly in use for the toxin of the minor group. 



Using a modified Romer method, we titrated the antitoxin 

 content of a group of young adults immunized against diphtheria 

 with toxin-antitoxin. We found 20 out of 26 had developed anti- 

 toxin in quantities varying from 1/30 unit up to 1/5, while three 

 developed only 1/50, and three failed to develop any immunity. 



We then ran Schick tests with regular and minor group toxins. 



