122 LABORATORY COURSE IN SERUM STUDY 



and perhaps none in 8 and 9, then the quantity contained in 

 Tube 11, namely 0.1 c.c. of the 1 to 10 dilution, is the antigenic 

 dose or unit. It is desirable to use 4 or 5 times this unit in the 

 test, and if this quantity does not exceed one third of the anti- 

 complementary dose determined in Series 1, the antigen is suitable 



for use. 



Series 4 



The object of Series 4 is of course to show that inactivated 

 normal sera do not fix complement in the presence of the antigen. 

 In practice no worker should be satisfied to test a new antigen 

 against merely one normal serum, but before using the antigen in 

 routine tests it should be used for some time parallel with an old 

 familiar antigen. 



Series 5 



Series 5 controls the positive and negative sera used in the 

 preceding series. They are carried out because under certain 

 circumstances sera become anticomplementary, especially if kept 

 for several days. If this occurs, the anticomplementary property 

 can usually be destroyed by heating to 56 C. However, occa- 

 sionally even inactivated sera may remain slightly anticomple- 

 mentary. Therefore these controls are indispensable. 



MATERIALS 

 Each student needs : 



1.0 c.c. antigen (undiluted). 

 10.0 c.c. complement (1-10). 

 15.0 c.c. 5 per cent sheep cells. 

 45 units amboceptor. 

 1.0 c.c. positive (+ + + +) serum. 

 1.0 c.c. negative serum. 



Salt solution. 

 25 half-inch test tubes. 

 5 one-inch test tubes. 

 8 one-c.c. pipettes. 

 1 two-c.c. pipette. 

 1 five-c.c. pipette. 

 1 test tube rack. 

 Electric fan. 



