48 



LABORATORY COURSE IN SERUM STUDY 



Tube (6) will show whether the three washings were sufficient to 

 remove all amboceptor from the fluid bathing the cells. Any excess of 

 amboceptor remaining unattached to the cells after the washing would 

 show in the supernatant fluid by laking. 



Tube (c) will show how much, if any, amboceptor was dissociated 

 after one hour at 37 C. 



2. VELOCITY OF AMBOCEPTOR ABSORPTION 



Red cells absorb their homologous immune-body very rapidly. 

 A knowledge of this is of great importance as the following ex- 

 periments show. 



A 



Take 3 c.c. of 5 per cent sheep corpuscles in a wide test tube and add 

 3 c.c. of diluted amboceptor drop by drop, shaking constantly (the 

 dilution of the amboceptor is such that 1 unit is contained in 0.5 c.c. ; 

 the unit here is taken as the minimal amount which lakes 0.5 c.c. of 

 cells). 



B 



Take 3 c.c. of diluted amboceptor and add 3 c.c. of 5 per cent sheep 

 cells drop by drop, shaking constantly. 



Set up two parallel series of five tubes each containing varying 

 amounts of guinea pig serum (1-10). 



Series 1 



Series 2 



Duplicate above with mixture B. 



Incubate one hour and compare results. 



The observed differences are probably explained by the fact that 

 the first cells which are added to B absorb nearly all the amboceptor, 

 leaving insufficient to sensitize the last cells added. 



