COMPLEMENT-FIXATION TEST IN TUBERCULOSIS 491 



Further discussion on Citron's tuberculin theory is reserved for the 

 chapter devoted to this subject. Evidence indicates, however, that 

 immunity in tuberculosis is not dependent solely upon the development 

 and presence of antituberculin, but that other antibodies are likewise 

 concerned. 



As a practical test, complement fixation has not been successful in 

 tuberculosis. As previously stated, this may be due to the fact that 

 antituberculin production is transitory and variable, and hence if the 

 amboceptors are absent or present in but very minute amounts, com- 

 plement fixation in vitro cannot occur. 



Considerable attention has also been given the preparation of the 

 antigen, in the belief that a special endotoxic substance or part of the 

 bacillus is required. Various antigens have been used, such as Bacillen 

 emulsion, old tuberculin, tuberculin filtrate, and a watery emulsion of 

 tubercle bacilli. A mixture of Koch's old and new tuberculins has also 

 been used. Antigen may also be prepared after the method of Besredka 

 (p. 474), in which the bacilli are dried, ground, and used as a fine suspen- 

 sion of the bacterial substance. 



More recently Hammer 1 has reported favorably upon an antigen 

 composed of an alcoholic extract of tuberculous tissue and old tuberculin. 

 The tissue is extracted for five days with four parts alcohol and filtered. 

 To each cubic centimeter of extract, 0.1 c.c. of old tuberculin is added; 

 the anticomplementary dose is determined, and one-half this amount is 

 used in conducting the main test. 



At present, however, complement-fixation tests have yielded in- 

 different results, although a test sufficiently delicate and constant to 

 permit early infections to be detected would be of inestimable value. 

 If the failures of the past have been due rather to faulty antigen than 

 to absence of tuberculin amboceptors, researches in the future will 

 probably solve the problem. 



THE COMPLEMENT-FIXATION TEST IN THE STANDARDIZATION OF 



IMMUNE SERUMS 



The technic of complement fixation has also been employed as one 

 means in effecting the standardization of antimeningococci and anti- 

 gonococcic serums. Since, however, the amount of complement-fixing 

 amboceptors in a serum is no index to its therapeutic and prophylactic 

 value, a measure of this one factor is not a reliable standard. 



1 Munch, med. Wochenschr., 1912, 59, 1750. 



