lipase. Or the presence of aatabolic materials may even 

 produce a change in the configuration of the fat mole- 

 cule. There is no doubt that some fat -free proteins are 

 antigens, but before we eliminate fats and lipoids from 

 the class of antigens, we must first eliminate them from 

 the various protein substances used as antigens. 



Although it would seem that some pure proteins are 

 antigens, it would also be equally apparent that other 

 pure proteins are not antigens. Starin (13), for 

 instance, working with a purified gelatin, was unable to 

 demonstrate antigenic function. It has been suggested 

 that antigenic properties of proteins rest with the aro- 

 matic radicals attached to the amino acids. Perhaps 

 these radicals have some affinity for fats and lipoids, 

 so that in the absence of such radicals there is also an 

 absence of fats; i.e., during the process of fractional 

 analysis those portions which bear the aromatic radicals 

 are" split off with fats, and the lower fractions, being 

 fat-free, are non- antigenic. The value and importance 

 of the fatty acids in treatment of diseases due to acid 

 fast bacteria have been demonstrated for several years. 

 Thus Chaulmoogra oil, sodium salts of the fatty acids of 

 cod- liver oil are used in treatment of tuberculosis and 

 leprosy (14). Walker and Sweeney (15) showed that the 

 fatty acids obtained from Chaulmoogra oil are specifi- 

 cally bactericidal for acid-fast micro-organisms, but 

 not for non-acid fast micro-organisms. Similarly, 

 Hollman and Dean (16) demonstrated the theraputic value 

 of esters of the fatty acids of Chaulmoogra oil in the 

 treatment of leprosy. These findings lend strength to 

 the theory that fats are intimately concerned in 

 immunological reactions. 



The most interesting work which has been done on 

 the antigenic nature of fats is found in the recent 

 experimental data contributed by Warden. This investi- 

 gator has been studying the problem from the experimen- 

 tal standpoint during a period of several years. In 

 1915 he suggested, as a result of his studies on the 

 relation between bacterial fats and proteins, that some 

 fats are in a lipoidal combination with protein and are 

 not hydrolysed until the nitrogen portion is thoroughly 

 broken up (17). In the same year, reporting further 

 results, using the gonococcus as the source of his 

 material, he found that the organic nitrogen of the 

 gonococcus did not seem to be altogether available as 

 antigen. The fats of the gonococcus, chemically iso- 

 lated, possessed a much higher antigenic power (18), 

 Later, (19) (20), it was found that the fats, as 



