SERUM DIAGNOSIS OF SYPHILIS. 



149 



extracts from apes were used so as to exclude the error. Even in this way complement 

 fixation was attained. Later on it was found unnecessary to inject the monkeys with 

 the extracts since after ordinary infection their serum would give complement fixation. 

 In this manner it was almost definitely established firstly, that these extracts contained 

 a substance specific for syphilis which could with most probability be considered a 

 luetic antigen, and secondly that infected apes possessed antibodies against this antigen. 



The next step was to try the reaction in man. The first experiments of 

 Wassermann, Neisser, Bruck and Schucht did not give the hoped for 

 returns. Although the reaction was obtained with human serum, the per- 

 centage of positive results was so small (see next chart) that its practical 

 value as a means of diagnosis offered no great help. Only in general 

 paralysis did the expectation seem promising. In about 80 per cent, of all 

 cases Wassermann and Plaut were able to demonstrate the luetic antibodies 

 in the cerebrospinal fluid. 



Schiitze's experiments in tabes led him to the same findings. Citron has obtained a 

 much smaller percentage of positive reacting cerebrospinal fluids in tabes. 



As it seemed that the means of diagnosis was not to be established by the 

 demonstration of the syphilitic antibody, Neisser and Bruck believed that 

 better results may possibly be achieved by the discovery of the luetic antigen 

 in the serum through complement fixation. 



This attempt too was unsuccessful. No antigen could be found, but the extracts of 

 red blood cells from syphilitic individuals when mixed with the serum of highly immunized 

 monkeys gave a positive complement fixation. Neisser and his co-workers concluded 

 therefrom that the erythrocyte extract contained the luetic antigen. Citron soon demon- 

 strated that the extracts of normal individuals gave a similar reaction and what was more 

 important, that this so-called blood antigen existed in the blood entirely uninfluenced 

 by mercurial treatment. Since these experiments, not much importance has been attached 

 to this reaction. 



Meanwhile the author working at the Kraus clinic proved by a large 

 series of experiments that luetic antibodies were present in almost all cases 

 of lues. The reaction is dependent upon two rules. 



The First. The longer the syphilis virus has acted upon the organism and 

 the more numerous its recurrent manifestations have been, the more fre- 

 quently will a positive reaction be obtained and the stronger will the anti- 

 body content of the serum be. 



The Second. The sooner a proper mercury therapy is instituted, the 

 more often it is repeated, and the shorter the interval since the last treatment, 

 the smaller will the antibody content of the serum be and the greater the 

 possibility of a negative reaction. 



These points were soon corroborated by numerous other workers in the 

 field, so that at the. present day, they can be taken as absolute facts. The 

 following chart will explain some of the statements aforementioned. 



