METHODS FOR CONDUCTING THE SYPHILIS REACTION 443 



ysis is less marked and variable (see Fig. 112). In from 15 to 20 

 per cent, of cases the cholesterinized extract shows a 50 per cent, or 

 more inhibition of hemolysis, whereas with the other two antigens the 

 reactions are negative. In our experience the majority of such 

 serums were taken from patients giving a frank history of syphilis of 

 many years' standing and from known cases undergoing treatment, 

 further therapy being indicated until the reaction finally becomes 

 negative when cholesternized extracts are used. In a small pro- 

 portion of cases a feebly positive reaction of 25 per cent, or less in- 

 hibition of hemolysis may be found with the cholesterinized extract 

 alone. Many of these reactions occur with serums of treated cases 

 of syphilis; on the other hand, a similar reaction may occur with 

 about 5 per cent, of normal serums, so that if the history and clinical 

 conditions are clearly negative, a slight degree of inhibition of hemoly- 

 sis (5 to 10 per cent.) with the cholesterinized extract and marked 

 hemolysis with the other two antigens may be interpreted as a negative 

 reaction. 



After a new antigen has been prepared and titrated, it should be 

 tested out in this manner by placing it in the series along with at 

 least two other older antigens of proved value, and used in the ex- 

 amination of a large number of serums before it is finally accepted as 

 reliable. 



TECHNIC OF THE THIRD METHOD 



As previously stated, it may be desirable to measure the quantity 

 of syphilis antibody in a patient's serum more accurately, especially 

 when observing the effect of treatment. This is readily accomplished 

 by using decreasing doses of serum with constant doses of antigen and 

 complement. In those tubes showing partial inhibition of hemolysis 

 the degree of hemolysis is determined by comparison with a hemo- 

 globin scale (Boas). 



The technic is quite similar to that followed in the second method. 



1. One antigen is employed, either an alcoholic extract of syphilitic 

 liver or acetone-insoluble lipoids. The same general rule as to dosage 

 is employed, namely, from two to four times the titrated antigenic 

 unit, providing these amounts are not more than one-fourth the 

 anticomplementary dose. 



2. 0.5 c.c. of each serum is heated to 55 C. for half an hour and 

 diluted 1 : 10 by adding 4.5 c.c. of salt solution. 



3. Fresh guinea-pig serum complement is diluted 1:20 as usual, 

 and used in doses of 1 c.c.; sheep corpuscles are made up in a 2.5 per 



