MODIFICATIONS OF THE WASSERMANN REACTION 483 



has proved quite delicate, but is open to the same error that may occur 

 whenever an active serum is used with a crude alcoholic organic extract 

 as antigen i. e., the appearance of false positive or proteotropic reac- 

 tions. As with the Noguchi reaction, using active serum, a negative 

 Hecht-Weinberg test has considerable diagnostic value in excluding 

 syphilis; a positive reaction must be, however, carefully controlled. 

 In performing the test I always use an extract of acetone-insoluble 

 lipoids as antigen. 



Since in the original Hecht-Weinberg 1 test there is no way of deter- 

 mining beforehand the amount of sheep corpuscles a serum may hemo- 

 lyze, Gradwohl 2 has modified the technic so that the hemolytic index 

 of each serum is determined before the corpuscles are added to the 

 main tubes. I conduct this test as follows : 8 Nine small sterile test-tubes 

 (10x1 cm.) are arranged for each serum and properly labeled; into each 

 is placed 0.1 c.c. of fresh unheated serum. To the first five tubes are 

 added respectively 0.1, 0.2, 0.3, 0.4, and 0.5 c.c. of a 5 per cent, suspension 

 of washed sheep cells; to the sixth, seventh, and eighth tubes are added 

 1, 2, and 3 units of antigen respectively, as determined by titration. 

 The last or ninth tube serves as the serum control. Sufficient normal 

 salt solution is added to each tube to bring the total volume to 1 c.c. 



After one hour's incubation at 37 C. the hemolytic index of each serum 

 is read in the first five tubes of each series (that is, the largest dose of 

 corpuscles just completely hemolyzed by each serum) and one-half the 

 indicated doses of corpuscles added to the remaining four tubes of each 

 series. After re-incubation for one-half to one hour, according to the 

 hemolysis of the controls, the results are read and recorded as in the 

 Wassermann reaction. 



The antigen titrations are very important because the activity of 

 human serum is quite sensitive to the inactivating influence of tissue 

 extracts. No antigen should be employed in this test without pre- 

 liminary titration with human serum to determine its anticomplementary 

 and antigenic units. The anticomplementary titration is conducted by 

 placing in a series of eight test-tubes the following amounts of antigen 

 of acetone-insoluble lipoids diluted 1 : 100: 0.2, 0.3, 0.4, 0.6, 0.8, 1.0, 

 1.2, 1.5 c.c., and 0.1 c.c. of the fresh and mixed sera of two non-syphilitic 

 persons; normal salt solution is added to 2 c.c. and the tubes incubated 

 for an hour at 37 C., when one-half the index of cells for the serum 

 is added to each tube. After a second incubation of an hour the anti- 



1 Wien. klin. Wchnschr., 1908, 21, 1742; ibid., 1907, 22, 265; find., 1909, 22, 338. 



2 Jour. Amer. Med. Assoc., 1914, 63, 240. 3 Jour. Immunol., 1916, 2, 23. 



