Serum Diagnosis of Syphilis. 



79 



From the foregoing it becomes at once evident that any system 

 of the complement fixation test in which definite and appropriate 

 amounts of these two vitally important reagents are not employed 

 is not delicate and accurate enough to be a reliable diagnostic 

 measure. 



Referring to the method of Wassermann I may state that it 

 has all the disadvantages arising from the presence of unknown, 

 but often considerably large amounts of natural antisheep ambo- 

 ceptor contained in human serum. Wassermann was quite una- 

 ware that the natural antisheep amboceptor is capable of being 

 reactivated by guinea-pig's complement, and hence he recommended 

 the use of two units of immune antisheep amboceptor of the rabbit 

 with the view of obtaining complete hemolysis. The reactivability 

 of the natural amboceptor by this complement has been dis- 

 covered since by Bauer who, in turn, proposed to utilize the 

 natural amboceptor and dismiss the use of the immune ambo- 

 ceptor. By systematic examination of more than loo speci- 

 mens of human sera in regard to the content of natural antisheep 

 amboceptor I found that it varies from almost none to as many as 

 twenty units in o. I c.c, the quantity usually employed for each 

 tube in the fixation test. Thus the method of Wassermann is 

 destined to give unreliable and inaccurate reactions. Bauer's modi- 

 fication is just as inaccurate as the original as it relies upon 

 unknown amounts of the natural amboceptor alone. 



The method which I have recently perfected is also a comple- 

 ment fixation test and differs from the Wassermann method in 

 employing an antihuman hemolytic system instead of an antisheep 

 hemolytic system. Thus the human blood corpuscles are to be 

 hemolysed by means of an antihuman amboceptor prepared in the 

 rabbit and the complement of the guinea-pig. I use two units of 

 the amboceptor for each tube. In this new system the danger of 

 introducing any uncalculated amount of the hemolytic amboceptor 

 is absolutely excluded. As the fixation test is carried out with 

 definite and uniform amounts both of the complement and the 

 amboceptor, the results obtained with different specimens and at 

 different occasions are all comparable with one another. The 

 sharpness of the reaction enables one also to follow the fluctuation 

 of the antibody content even to a fraction of one unit. 



