138 



Scientific Proceedings (83). 



In studying the role of cholesterin in the preparation of antigen 

 we came to the following conclusions : 



The apparent superiority of reinforced antigens is not due 

 to the heightened specificity of these antigens, but to a heightened 

 anticomplementary power of the same. 



In addition, cholesterol retards and, if used in sufficient con- 

 nection, greatly protects the blood cells from the action of hemo- 

 lytic agents, thus further increasing the tendency towards a 

 higher percentage of positive reactions. 



That this influence of cholesterol is not specific is evidenced 

 by the fact that more recently different authors noted the occur- 

 rence of nonspecific fixations obtained with reinforced antigen in 

 a high percentage of normal cases. 



The erroneous procedure recommended by some of the recent 

 texts of using Yi to Vk of anticomplementary dose of reinforced 

 antigen in the test may increase the occurrence of nonspecific 

 fixations up to 40 per cent, of normal cases, as reported by some 

 of the investigators. 



On the other hand we found that removing all the cholesterol 

 from the tissue extracts actually improves them for the use in 

 the complement fixation test. 



By redissolving and reprecipitating the acetone insoluble frac- 

 tion of tissue lipoids one does not diminish its antigenic value, 

 while one very markedly decreases its anticomplementary power. 



The antigen prepared in this way can be used in the amount 

 10 or even 20 times smaller than the dose fixing 1 H E unit 1 of 

 complement, and yet even such minute amounts of antigen may 

 contain considerably more than 10 antigenic units. 



In general we can not but discourage the use of cholesterinized 

 antigens in favor of reprecipitated acetone insoluble fraction of 

 tissue lipoids free from cholesterol. 



1 Bronfenbrenner and Schlesinger, Am. Jour, of Syphilis, April, 1917. 



