178 TECHNIQUE OF THE COMPLEMENT FIXATION METHOD 



Wassermann's modification of the Bordet-Gengou method was first 

 practically employed for the titration of the therapeutic meningococcus. 

 serum. One cannot, however, correctly judge the prophylactic or curative 

 value of a serum by its antibody content as they do not run hand in hand 

 (R. Kraus, F. Meyer and Garbat, Citron.) 



ffl. Serum Diagnosis of Syphilis. 



a. Wassermann's Technique. 



The technique of this reaction as carried out in Wassermann's labora- 

 tory is practically identical with that just described for the diagnosis*of 

 bacterial infections. The preparation of the antigen varies slightly. 



The liver obtained from a syphilitic fetus is weighed and cut up into fine pieces. 

 Four times its weight of 1/2 per cent, of carbolic solution in saline is added, the mix- 

 ture placed in a brown bottle and shaken for twenty-four hours. It is then cen- 

 trifugalized until the larger liver remnants settle to the bottom and a somewhat turbid 

 fluid remains above. The latter is poured off into a brown bottle and placed in the 

 ice-box. After several days of sedimentation, the fluid assumes a yellowish-brown 

 opalescence and can now be used as a luetic antigen. It should not be exposed to light 

 or heat, should not be shaken, and its contents should not be pipetted off, but care- 

 fully poured off without disturbance to the sediment. 



By titration of the extract, that dose is determined which does not of 

 itself bind complement. Only such extracts are kept which in the dose of 

 0.4 c.cm. do not interfere with hemolysis. 



Control tests should also be made to ascertain whether the organ extract 

 has any tendency of its own to hemolyze red blood cells without the 

 presence of complement or hemolysin. 



Not every luetic extract can serve as antigen for complement fixation. 

 A number of other substances, both normal and pathological, may be 

 extracted from the luetic liver besides that agent necessary for the 

 Wassermann test. These undesired ingredients may interfere with the 

 efficiency of the extract. For this reason a great number of known posi- 

 tive and negative sera should be tested with each new extract, and only 

 if the results are absolutely correct should it be employed as antigen. 



In the early work of Wassermann the antigen was described as deteriorating very 

 easily; its activity would either be entirely destroyed or it would become anticomple- 

 mentary. The author is firmly convinced that these changes are brought about by 

 careless handling of the extract or its exposure to light. If properly taken care of, its 

 activity remains constant. 



From practical experience, it has been found that extracts which must 

 be used in amounts less than o.i c.cm. are as a general rule unsatisfactory. 



