406 IMMUNOLOGY 



Hemolytic Titration of Bacterial Antigen 



In the above protocol it will be noted that 0.5 c.c. of a 1 :2 dilu- 

 tion of antigen was the least amount of antigen producing some 

 hemolysis. Kolmer would call this the hemolytic unit. 



The next protocol is given to illustrate one method Kolmer 

 and others have used to determine the smallest amount of antigen 

 that produces a slight inhibition of hemolysis. Tliis amount is 

 called the anticomplementary unit. The results are illustrated in 

 Plate YI, Fig. 1, except that Tubes 11 and 12 are not shown on 

 the plate. 



The anticomplementary unit in the above protocol would be 0.5 

 C.C. of a 1 :2 dilution. Kolmer regards the anticomplementary 

 titration as very important and suggests that it be done at frequent 

 intervals with most bacterial antigens. 



The next protocol is an example of antigenic titration according 

 to a method suggested by Kolmer. The results are illustrated in 

 Plate VI, Fig. 2, except that the serum control Tube 11 and the 

 control on the hemolytic system Tube 12 are omitted from 

 Plate VI, Fig. 2. 



In the accompanying j)rotocol the antigenic unit, i.e., the least 

 amount of antigen giving a + + + + fixation of complement (in- 

 dicated l)y complete inhibition of hemolysis), is contained in 

 Tube 8. This unit then is 0.5 c.c. of a 1:200 dilution of antigen. 

 (See Plate VI, Fig. 2.) 



If positive serum is not available, Kolmer suggests employing 

 a dose of antigen in the test, equivalent to one-third the anti- 

 complementary dose. Referring to the anticomplementary titer 

 given earlier, it is found to be 0.5 c.c. of a 1 .-2 dilution of antigen. 



