928 EXPERIMENTAL INFECTION AND IMMUNITY 



4. Into two centrifuge tubes place four units of amboceptor and 1 c.c. of cor- 

 puscle suspension. Mix and place one tube in a glass of cracked ice, leaving the 

 other at room temperature. After one hour centrifuge both. Pipet the supernatant 

 fluids into two separate test-tubes. 



5. To the sedimented corpuscles in both centrifuge tubes add 1 c.c. diluted com- 

 plement serum. Mix well. Incubate tubes for one hour at 37 C. 



6. To the supernatant fluid of each tube add 1 c.c. corpuscle suspension and 1 

 c.c. of diluted complement serum. Mix. Incubate tubes for an hour. 



(a) In which tubes has hemolysis occurred? 



(b) How do you explain the results? 



(c) Discuss the prevailing views of amboceptor action. 



EXPERIMENT 79. A FURTHER STUDY OF THE MECHANISM OF AMBO- 

 CEPTORS 



1. In a centrifuge tube place two hemolytic doses of antisheep hemolysin and 2 c.c. 

 of fresh guinea-pig complement diluted 1 : 20. Place in a glass of cracked ice until the 

 mixture is thoroughly chilled. Then add 2 c.c. of a 1\ per cent, suspension of sheep 

 cells (also chilled). Mix and keep at a low temperature for an hour, centrifuge 

 thoroughly, and pipet the supernatant fluid to a separate test-tube. 



2. In a second centrifuge tube place 2 c.c. of diluted complement and 2 c.c. cor- 

 puscle suspension. Keep at room temperature for one hour, centrifuge, and pipet the 

 supernatant fluid into a test-tube. 



3. Proceed as follows: To 2 c.c. of the supernatant fluid from the first centrifuge 

 tube add 1 c.c. corpuscle suspension; to the remaining 2 c.c. add 1 c.c. corpuscle sus- 

 pension and two units of amboceptor; to the sedimented corpuscles add 2 c.c. of 

 diluted complement serum. 



4. To 2 c.c. of the supernatant fluid from the second centrifuge tube add 1 c.c. 

 corpuscle suspension; to the remaining 2 c.c. add 1 c.c. corpuscle suspension and two 

 units of hemolytic amboceptor. 



5. To the sedimented corpuscles in both centrifuge tubes add 1 c.c. complement 

 serum and 1 c.c. salt solution. Mix well. 



6. Shake all tubes gently and incubate for one hour at 37 C. 



(a) In which tubes has hemolysis occurred? 



(b) Does complement unite directly with corpuscles? 



(c) What evidence have you that amboceptors unite directly with 

 corpuscles? 



(d) What is meant by the term " sensitizing corpuscles"? 



(e) Is complement-amboceptor activity apparent at low temperature? 



(f) What temperature best favors complement-amboceptor activity? 



EXERCISE 3*. AMBOCEPTORS AND COMPLEMENTS. HEMOLYSINS 



(Continued) 



EXPERIMENT 80. NATURAL HEMOLYSINS. REMOVAL OF NATURAL 

 HEMOLYSINS 



1. Secure 1 c.c. of serum from the blood of five different persons and inactivate 

 in the water-bath. 



