VALUATION OF COMPLEMENT DEVIATION 283 



to "Bordet's antibody/' whether it is identical 

 with other amboceptors or not. 



It will be readily seen that the reaction of com- practical 

 plement fixation like other immune reactions be- Reaction. 

 tween antigen and antibody may be used for the 

 identification of either of the two bodies concerned. 



The complement fixation test has been used Biologic Test. 

 especially by Neisser and Sachs similarly to the 

 precipitin test for the differentiation of proteins. 



Animals are immunized to a certain protein 

 and an antiserum is thus obtained. A titration is 

 then made with known homologous antigen and 

 antibody, in varying quantities, to determine the 

 amount of antiserum necessary to produce com- 

 plement deviation. The quantity of antiserum 

 found by titration to be necessary for complement 

 fixation in the presence of homologous antigen, is 

 then added to the serum or protein to be tested. 

 If this protein and the antiserum are homologous, 

 a complement fixation will result. The method 

 has been criticized because of its extreme delicacy. 

 It is estimated that amounts of protein substances 

 will give a complement fixation test which are 

 present in one-millionth the quantity required for 

 a precipitin test. Uhlenhuth advises the control 

 of the method by the precipitin test. Although 

 other antigens such as bacteria may be identified 

 by complement fixation, the existence of easier 

 methods makes complement fixation of little value. 



The existence of easier methods of diagnosis AS Antibody 

 results in infrequent use being made of the com- n 

 plement deviation reaction as a means of diagnosis 

 in infections with organisms capable of cultiva- 

 tion. The presence of the reaction has been 



