AMBOCEPTORS AND COMPLEMENTS 849 



C. for half an hour. Dilute 1:100 by adding 0.1 c.c. serum to 9.9 c.c. normal salt 

 solution. 



2. Prepare 40 c.c. of a 5 per cent, dilution of fresh guinea-pig serum to be used for 

 complement. Prepare 40 c.c. of a 2^ per cent, suspension of washed sheep cells by 

 adding 1 c.c. of corpuscles to 39 c.c. of normal salt solution. 



3. Proceed with the titration as given in the text on page 375. If the smallest 

 dose, viz., 0.1 c.c. of the 1 : 100 dilution, completely hemolyzes the corpuscles, it will be 

 necessary to retitrate with a dilution of 1 : 1000. 



(a) Is it necessary to use exactly the same amounts of complement 

 and corpuscles in all tubes and if so, why? 



(b) If hemolysis did not occur at all in this experiment, what fac- 

 tors may be at fault? 



(c) If the corpuscle control were completely hemolyzed, what de- 

 duction would you draw? 



(d) What is the amboceptor unit of this serum? 



EXPERIMENT 73. QUANTITATIVE FACTORS IN SERUM HEMOLYSIS 



1. Having determined the amboceptor unit of the above antisheep immune serum, 

 proceed as follows: 



2. To a series of four test-tubes add an amount of immune serum equaling one, 

 two, three, and five amboceptor units respectively. To each tube add 0.5 c.c. of the 

 1 : 20 dilution of complement serum. This amount is just half the dose of comple- 

 ment used in titrating the amboceptor. Add 1 c.c. of a 2^ per cent, suspension of 

 sheep cells to each tube and sufficient salt solution. 



3. In a second series of four test-tubes place one half an amboceptor unit and the 

 following amounts of diluted complement serum: 1 c.c., 2 c.c., 3 c.c., and 4 c.c. Add 



1 c.c. of the suspension of sheep corpuscles and sufficient salt solution to make the 

 total volume in each tube about equal. Incubate for one hour and read the results. 



4. In a third series of four test-tubes place one amboceptor unit, 1 c.c. of com- 

 plement serum (1:20), and the following amounts of corpuscle suspension: 1 c.c., 



2 c.c., 3 c.c., and 4 c.c. Add sufficient salt solution to make the total volume in each 

 tube about equal. 



5. Prepare a corpuscle control with 1 c.c. of suspension and 4 c.c. normal salt 

 solution. 



6. Shake all tubes gently and incubate for two hours at 37 C. 



(a) Can an excess of amboceptor make up for a deficiency in comple- 

 ment? 



(b) Can an excess of complement make up for a deficiency of ambo- 

 ceptor? 



(c) What happens when an excess of corpuscle suspension is used? 



(d) Discuss the importance of quantitative factors in serum hem- 

 olysis. 



54 



