158 MODERN BIOLOGIC THERAPEUSIS 



ates rapidly if exposed to a warm temperature, 

 but may be preserved for some time by freez- 

 ing. Complement is usually used in a 10 per 

 cent solution made with physiologic salt solu- 

 tion. 



Red Cells Bed blood cells from various ani- 

 mals may be used, but the cells must be washed 

 free from serum with physiologic salt solution. 

 In our laboratories, sheep's cells washed six 

 times are used in a 5 per cent suspension. A 

 sheep is bled from the jugular vein into a sterile 

 bottle containing glass beads and, before the 

 blood coagulates, it is thoroughly shaken for the 

 purpose of defibrination. The cells are washed 

 by mixing a small amount of the blood with 

 physiologic salt solution in graduated centri- 

 fuge tubes, and the mixture is centrifugalized 

 long enough for the red cells to settle to the bot- 

 tom of the tubes. 



Hemolytic Amboceptor Hemolytic ambocep- 

 tor is obtained by successive intravenous inocu- 

 lations of a rabbit with thoroughly washed 

 sheep's red cells hence the name, Anti-Sheep 

 Amboceptor. Before being used in the test, the 

 hemolytic amboceptor and the antigen must first 

 be standardized by preliminary titrations in or- 



