120 LABORATORY COURSE IN SERUM STUDY 



5. SERUM CONTROLS 



Tube Normal Serum Complement 1-10 



17 0.1 c.c. 0.5 c.c. 



18 Q.2 c.c. 0.5 c.c. 



Syphilitic (+ + ++) Serum 



19 0.1 c.c. 0.5 c.c. 



20 0.2 c.c. 0.5 c.c. 



The volume is made to 2 c.c. as nearly as possible in all the tubes. 



All tubes are put in water bath for one hour. Then 5 c.c. of 5 per 

 cent sheep cells and two units of amboceptor are added to each tube (ex- 

 cept 2 tube 7) and the tubes are all returned to the water bath for 

 thirty minutes. 



CONCLUSIONS TO BE DRAWN FROM THE ABOVE 

 Series 1 



The anticomplementary dose is that quantity of antigen which 

 shows the slightest inhibition of laking. The amount of antigen 

 used in the test must under no circumstances exceed one half of 

 this amount and is usually taken as one third of it. Thus if 

 Tube 5 containing 1.6 c.c. of the 1 to 10 antigen shows a faint 

 haze of undissolved red cells, then the quantity used in the tests 

 should not exceed 0.5 c.c. 



Series 2 



An antigen which is hsemolytic in itself in Tube 7 is rejected 

 as useless. When the extractions are made of normal heart this 

 occurrence is rare. 



Series 3 



The antigenic dose is the smallest amount that gives com- 

 plete inhibition in the presence of syphilitic serum. This is tested 

 in Tubes 8 to 13. In order that an antigen be of value the 

 antigenic dose must be considerably smaller than the anticom- 

 plementary quantity determined in Series 1. It is desirable in 

 the tests to use an amount of antigen containing at least several 

 antigenic units. Thus, if the antigen tested shows complete in- 

 hibition in Tube 11 and merely partial inhibition in Tube 10, 



