204 IMMUNOLOGY 



The contents of each tube should be mixed and incubated in a 

 water bath at 37° C. for 1 hour. The unit is the highest diki- 

 tion of hemolysin that gives complete hemolysis. Plate IV shows 

 such a titration in w^hich tube 5 (1:5,000) contains 0.5 c.c. of the 

 highest dilution giving complete hemolysis. The unit or titer in 

 this case is 0.5 c.c. of a 1 :5,000 dilution. 



Complement Titration. — For complement titration Kolmer uses 

 a 1 :30 dilution of complement and always titrates this in the 

 presence of a test dose of antigen contained in 0.5 c.c. of saline. 

 He makes a point of using only cold saline in the titration. The 

 titration requires 9 tubes for the varying amounts of complement 

 shown in Plate IV, 2 and a tenth tube containing only saline and 

 red cells (not shown in the plate). He sets up the complement 

 titration according to the following protocol : 



CoMPLEjrENT Titration 



Unit of Complement. — The tube containing the least amount 

 of complement that shows complete liemolysis is said to contain one 

 exact unit of complement. In the illustration (Plate IV, 2) tube 

 four contains the least amount of complement in which complete 

 hemolysis results. In this example the exact unit is 0.25 c.c. of a 

 1 :30 dilution. Kolmer defines a full unit as 0.05 c.c. more than 

 an exact unit. This would be contained in tube five to which 

 0.30 c.c. .of the 1 :30 dilution of complement had been added. 



The method of antigenic titration used by Kolmer and tlie 

 various standards he has set up will be discussed in the chapter 

 oil complement fixation. 



