MODIFICATIONS OF THE WASSERMANN REACTION 475 



as positive when lysis is incomplete vrith 2 units of complement, in addition 

 to the amount absorbed by the serum alone. More strongly reacting serums 

 will absorb from 3 to 8 units of complement, and not infrequently more; 

 these sera may be retested with 8, 10, 12, etc., units of complement, 

 but the employment of these large doses routinely is not justified because 

 of the large amount of complement used, and the complement-fixing 

 power of the majority of sera are readily measured with 2 to 8 units. 

 The method of reading is best shown in Table 15b and Fig. 117. 



Cases of syphilis progressing favorably with the administration of 

 specific remedies show less and less complement fixation until a negative 

 reaction is secured. A large number of comparative tests employing 

 the original Wassermann and this reaction with the same antigen have 

 shown that a serum yielding a -f + + + result in the original Wasser- 

 mann reaction may show anywhere from 2 to 8 units of fixation with this 

 technic. 



MODIFICATIONS OF THE WASSERMANN REACTION 

 MODIFICATION OF NOGUCHI 



Among the large number of modifications of the original syphilis 

 reaction that have been devised, that of Noguchi has proved of dis- 

 tinct value. In this method an antihuman hemolytic system is 

 employed that eliminates one possible source of error, due to the 

 natural antisheep amboceptor in human serum. 



Noguchi advocated the use of active serum for this test, with an 

 antigen of acetone-insoluble lipoids. Active serum yields a more 

 delicate reaction, but may give false or proteotropic complement 

 fixation, especially when crude alcoholic extracts are used as antigens. 

 Before I began using cholesterinized alcoholic extracts in making the 

 Wassermann reaction I not infrequently found that the Noguchi test 

 with active serum was more delicate than the Wassermann reaction, 

 but with cholesterinized extracts the results ran closely parallel. It 

 is a good practice to conduct both a Wassermann and a Noguchi test 

 with each serum, as a negative Noguchi test with active serum is a 

 better indication of the absence of syphilis than is a negative Wasser- 

 mann reaction. A positive Wassermann reaction, however, is better 

 evidence of the presence of syphilis than is a positive Noguchi reaction, 

 because of the possibility of false complement fixation occurring in 

 the latter when active serums are used. I may state, however, that 

 when a good antigen of acetone-insoluble lipoids is used, the per- 

 centage of false reactions is relatively small, being less than 2 per 



