THE PREPARATION OF BACTERIAL ANTIGENS * 



C. O. MELICK, PH.D. 

 (From the Laboratory of Preventive Medicine, University of Chicago.) 



The power of the so-called "antibodies" to react selectively 

 with the protein antigens employed in their production, occa- 

 sioned the early use of these "bodies" as reagents in the de- 

 tection of differences or similarities existing between two or 

 more proteins. In extension, the method was also early applied 

 to define the closeness of the relationship between cells, as dis- 

 played by the degree of the similarity of their constituent 

 proteins. 



This application was most extensively made in the field of 

 bacteriology and has allowed a biological classification of bac- 

 teria more extensive than that afforded by differences in mor- 

 phology, growth and pathogenicity. The extent of this use 

 of the antibody-antigen reaction has led to a multiplicity of 

 modifications of the method first employed. But although 

 these modifications have in general been directed toward a re- 

 finement and possible standardization of the technic, certain 

 phases remain relatively crude and conducive to error both in 

 experiment and in interpretation. Two distinct complications 

 in the methods now practised are; first, the tremendous ad- 

 mixture of non-essential substances complicating the condi- 

 tions of reaction both physically and chemically; and, secondly, 

 the chemical instability of the essential reacting substances. 



It is the purpose of this paper to discuss these complicating 

 factors in the antibody-antigen reaction and to outline methods 

 which I have used successfully in eliminating such complica- 

 tions. 



* Received for publication June 14, 1922. 



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