1 86 TECHNIQUE OF THE COMPLEMENT FIXATION METHOD 



Not before an absolutely negative reaction has been attained should specific 

 therapy cease. 



Several authorities consider only such tests as positive where there is complete 

 absence of hemolysis. This principle is proven as incorrect by their own statistics; 

 a great number of their surely syphilitic cases give a negative reaction. 



If the third tube (serum control) does not hemolyze, the test can be considered 

 neither positive nor negative. Very frequently the third tube of very strongly positive 

 cases will hemolyze very much more slowly than negative cases; these tests must there- 

 fore remain in the incubator for a longer period than the negative or weakly positive 

 ones and until the serum tube is completely hemolyzed. 



Other Modifications of Wassermann's Technique. 



On account of the somewhat complex technique of the reactions 

 numerous attempts have been made to simplify the test in one way or 

 another. The greatest difficulty lay in the preparation of a suitable 

 antigen. From the sundry modifications and improvements made in this 

 respect, perhaps the most important was announced simultaneously by 

 Landsteiner, Mtiller and Potzl, and Forges and Meier. 



They showed that by alcoholic extraction of luetic and even normal 

 organs of human beings and lower animals, substances were obtained 

 which could be used as a substitute for the aqueous syphilitic antigen. 

 The belief therefore arose that the active agents in the luetic extract belong 

 to the class of lipoids, and Forges and Meier endeavored to isolate them 

 from the serum. Thereupon it became evident that lecithin could replace 

 the antigen, but only up to a certain point. Further study by H. Sachs 

 led to the adoption of entire formulae for artificial antigens. 



The new principle disclosed by these discoveries led to many modifications in the 

 preparation of the antigen, the main advantage of which consisted in bringing the 

 reaction into more general use and application. The previous necessity of making an 

 extract from the liver of a luetic fetus somewhat limited this. The Wassermann reac- 

 tion became in a short period of time much more popular, although one could not adhere 

 to it with the same idea of specificity as before. 



Other changes in the reaction referred to the serum for examination. 

 H. Sachs demonstrated that the inactivation at 56 C. destroyed a great 

 part of the luetic "reagine." The dispensation of the latter was therefore 

 recommended. It soon became evident, however, that by so doing a 

 great number of normal and non-luetic pathological sera especially from 

 carcinoma cases gave a positive reaction. // is best therefore that this 

 modification should by all means be discarded. 



As all fresh sera contain complement, the addition of guinea-pig's 

 complement seemed superfluous if the serum for examination is employed 

 in an active form. The following combination was therefore proposed: 



