156 ANTIGENS AND THE TECHNIC OF SERUM REACTIONS 



in the erythrocyte antigen through the specific amboceptor or 

 hemolysin. 



The method of complement fixation may be employed to examine 

 sera for specific antibodies, using a known antigen, or to test suspected 

 antigens with sera containing specific antibodies. The most practical 

 application of the method in medicine is the serum diagnosis of syphilis, 

 glanders, and other bacterial infections. 



The Technic of Complement Fixation. The technic of complement 

 fixation is simple in principle, but it requires the most scrupulous 

 attention to details. All glassware must be neutral in reaction, 

 chemically clean, and bacteriologically sterile. Physiological salt 

 solution (0.85 to 0.90 per cent. C.P. NaCl in neutral distilled water) 

 used for washing red blood cells and for dilutions should be sterile 

 and stored in clean containers. 



The Wassermann Serum Diagnosis of Syphilis. Five elements enter 

 into the Wassermann test for syphilis : the antigen, suspected syphilitic 

 serum, complement, and a hemolytic system consisting of red blood 

 cells and specific immune hemolytic serum (hemolysin). 



Preparation and Standardization of Antigen. The antigen originally 

 employed by Wassermann and his collaborators was an aqueous 

 extract of syphilitic tissue which was prepared by suspending one part 

 by weight of finely comminuted liver of a syphilitic fetus 1 in five parts 

 of physiological salt solution containing 0.5 per cent, phenol as a 

 preservative. After several days' violent agitation in the dark it is 

 strained through several layers of cheesecloth to remove coarser par- 

 ticles and stored in amber bottles in the refrigerator. Sedimentation 

 takes place until a brownish, slightly opalescent fluid remains, which 

 is the luetic antigen. 



Later work 2 showed that alcoholic extracts of luetic liver were more 

 stable than watery extracts. The specific reacting component, accord- 

 ing to Forges and Meier, is lipoidal in nature, and in this sense it is 

 not biologically specific; The fixation of complement appears to 

 depend upon a substance in the antigen, lipoidal in nature, which 

 effects a union of antigen, immune body and complement. Citron 

 has proposed the term "lues reagine" for this substance. Alcoholic 

 extracts of syphilitic liver are prepared by shaking finely comminuted 

 liver with ten times the weight of absolute alcohol for a few days, 



1 The tissue is examined for the specific organism; if Treponemata are abundant it 

 is converted into antigen, otherwise it is discarded. 



2 Especially by Forges and Meier, Berl. klin. Wchnschr., 1908, No. 15. 



