PREPARATION OF BACTERIAL ANTIGENS 5 



Olitsky and Bernstein, 1 in their studies of such reactions, 

 found that the injection of serum-grown bacteria into animals 

 resulted in the production of a precipitating serum versus the 

 serum present in the medium. The antiserum thus formed 

 reacted with suspensions of other species of bacteria grown on 

 the same serum medium, in regard to precipitation, agglutina- 

 tion, and complement fixation. Their obvious conclusion was 

 that the bacteria themselves were the carriers of the serum 

 proteins -of the culture medium in sufficient quantities to func- 

 tion as complicating antigens. 



In a later report, 2 the same authors were able to show that 

 when an immune serum was developed by injections of bac- 

 teria grown on "serum" medium and was inoculated into 

 guinea pigs, it sensitized the cells of the animal not only to the 

 bacteria but also to the protein present in the medium upon 

 which the bacteria were grown. 



These authors are of the opinion that in addition to the 

 traces of culture medium proteins which are carried over as an 

 admixture, certain of the serum proteins of the medium are 

 actually absorbed by the bacterial cells. 



While I do not care to discuss this latter conclusion, the 

 results themselves demonstrate the necessity of excluding as 

 far as possible from bacterial antigen preparations all proteins 

 which are not actual constituents of the bacteria themselves. 

 I am convinced that the methods commonly used in preparing 

 bacterial antigens are not satisfactory from this point of view 

 and that fine distinctions based upon their use are not reliable. 



For these reasons, in my own studies of the colon-typhoid- 

 intermediate group I sought to cultivate the organisms in 

 media containing no proteins and wish to present here the 

 methods by which this was accomplished. The actual an- 

 tigenic variations of the organisms so grown as regards com- 

 plement fixation at periodic intervals are the basis of a future 

 publication. 



Comparative tests of a number of non-protein synthetic 

 media resulted in favor of a modification of Uschinsky's me- 

 dium, in the preparation of which especial attention was 

 given to the purity of the reagents and to the final degree of 



