484 THE TECHNIC OF COMPLEMENT-FIXATION REACTIONS 



complementary unit is read as the smallest dose of antigen producing 

 inhibition of hemolysis. The antigenic titration is conducted in the same 

 manner with the serum of one or two syphilitic persons and the follow- 

 ing doses of antigen (1 : 100) : 0.05, 0.1, 0.15, 0.2, 0.25, and 0.3 c.c. The 

 antigenic unit is the smallest amount giving complete inhibition of 

 hemolysis. 



MODIFICATION OF STERN 



Margaretta Stern devised a modification of the Wassermann reac- 

 tion, using fresh active serum and the patient's complement, and over- 

 coming non-specific reactions by using f to -|- of the usual dose of 

 extract, and three or four times the amboceptor unit. This method is 

 open to defects inherent in the use of variable amounts of complement 

 and excessive amounts of hemolytic amboceptor, which makes it im- 

 possible to test a specimen a few days after it has been collected. 



MODIFICATION OF TCHERNOGUBOU 



Tchernogubou proposed an antihuman hemolytic system with active 

 serum. Blood is collected in sodium citrate, and therefore contains 

 erythrocytes, complement, and syphilis antibody if the patient is luetic. 

 Antigen is added, and after sufficient time has elapsed for fixation of 

 complement to take place, antihuman amboceptor is added to test for 

 free complement. There are many objections to this method, the chief 

 ones being the variable amount of complement present in human serum, 

 the large amount of hemolytic amboceptor required, the absence of a 

 suitable control on the antigen, and the fact that old blood is entirely 

 unsuited for making the test. 



Tchernogubou has also proposed a system in which the natural 

 amboceptor and complement of human serum are utilized against 

 guinea-pig corpuscles. These factors are so variable that this modified 

 test has been largely abandoned. 



MODIFICATION OF DETRE AND BREZOVSKY 



In this modification an antihorse hemolytic system is used with 

 rabbit's complement. The chief objections are the variations in the 

 activity and fixability of rabbit complement, and the difficulty of ob- 

 taining horse blood. In addition to these, this method possesses no 

 advantages over Wassermann's antisheep system. 



MODIFICATION OF BROWNING AND MACKENZIE 



These investigators use an antiox hemolytic system, and have 

 modified the original Wassermann technic so as to make the method an 



