394 PHENOMENON OF COMPLEMENT FIXATION 



serum and the serums of tuberculous persons. Complement fixation 

 occurred under certain circumstances, and these are discussed more 

 fully in Chapter XXIV. These investigations finally led to the serum 

 diagnosis of syphilis, in which the antigen was supplied by tissues 

 containing large numbers of the Spirocheta pallida. By furnishing the 

 antigen it was hoped that the luetic antibody could be detected in the 

 body-fluids through the absorption of complement, by the union of the 

 antigen and its antibody in the complement-fixation test. Although 

 the primary results were somewhat discouraging, the possibility was 

 shown to exist, and while the original theories regarding the specific 

 nature of the antigen-antibody reaction have been modified by subse- 

 quent discoveries, nevertheless this reaction of Wassermann, Neisser 

 and Bruck, and Detre has proved itself one of the most valuable diag- 

 nostic procedures known. 



THE ORIGINAL COMPLEMENT-FIXATION METHOD OF BORDET 



In a paper published in 1901 Bordet 1 gives the results attained with 

 three different antigens and their respective antiserums pest, typhoid, 

 and Proteus vulgaris. The details of the technic employed with an 

 antigen of pest bacilli and an antipest horse serum are given. 



(a) The antigen consisted of twenty-four-hour cultures of .pest bacilli 

 in normal salt solution, making a somewhat concentrated emulsion. 



(6) The antipest horse serum was heated for half an hour at 56 C., 

 to remove the alexin or complement. Normal horse serum (heated) 

 was also employed as a negative control. 



(c) As alexin, the fresh serum of a normal guinea-pig was used. 



(d) The substance sensibilisatrice or hemolysin consisted of the inac- 

 tivated serum of a guinea-pig injected with rabbit's red blood-cells. 



(e) The corpuscles of the rabbit were washed, to free them of alexin, 

 and were used as the indicatory antigen. 



To 0.4 c.c. of the pest emulsion 1.2 c.c. of inactivated antipest 

 serum and 0.2. c.c. of guinea-pig alexin were added. This mixture was 

 allowed to remain at the ordinary laboratory temperature (18-20 C.) 

 for several hours. In order to ascertain whether or not the alexin had 

 been absorbed, hemolysin and erythrocytes were added to the mixture. 

 This was accomplished by sensitizing about 20 drops of washed rabbit's 

 cells with 2 c.c. of inactivated hemolysin for about fifteen minutes, and 

 adding two drops to each of the test-tubes. Hemolysis did not occur 

 1 Bordet: Ann. de 1'Inst. Pasteur, 1901, xv, 19. 



