AMBOCEPTORS AND COMPLEMENTS 929 



2. Remove 0.5 c.c. of serum from each to five separate centrifuge tubes and add 

 4.5 c.c. of 2}^ per cent, suspension of sheep cells to each. Shake gently and after 

 half an hour at room temperature centrifuge thoroughly and pipet the supernatant 

 dilute serum to separate tubes. Do not discard the corpuscles in the centrifuge 

 tubes. 



3. To each of the remaining 0.5 c.c. amounts of serum add 4.5 c.c. salt solution 

 and place 1 c.c. and 2 c.c. into two test-tubes respectively (0.1 c.c. and 0.2 c.c. undi- 

 luted serum). 



4. Into two more test-tubes place 1 and 2 c.c. respectively of the diluted serum 

 which has been treated with corpuscles. 



5. Add to each tube 1 c.c. of guinea-pig complement (1:20), 1 c.c. of 2^ per 

 cent, suspension of sheep cells, and sufficient salt solution. Shake gently and incu- 

 bate for one hour. 



6. To the sedimented corpuscles in the centrifuge tubes add 2 c.c. of diluted com- 

 plement serum and sufficient salt solution. Shake gently and incubate for one hour. 



(a) Has hemolysis occurred with the untreated serums? 



(b) How do you explain the results? 



(c) Has hemolysis occurred with the treated serums and if not, why 

 not? 



(d) Has hemolysis occurred with the corpuscles used in treating 

 the serums and why? 



(e) Of what practical importance are natural hemolysins? 



(f) Is natural antihuman hemolysin ever found in human serums? 

 What are they called? 



Note. The quantity of natural amboceptor in any of these serums 

 may be determined by the method of titration given in the text. In 

 choosing five serums at random it may be possible that some will not 

 show an appreciable amount of natural antisheep amboceptor. 



EXERCISE 32. AMBOCEPTORS AND COMPLEMENTS (Continued) 

 EXPERIMENT 81. HEMOLYTIC COMPLEMENT 



1. After giving a rabbit three intravenous injections of 5 c.c. of a 10 per cent, 

 suspension of washed sheep cells at intervals of three days, remove three cubic centi- 

 meters of blood from an ear and separate the serum. Dilute the serum 1 : 10 with 

 salt solution. 



2. Into four test-tubes place 1 c.c. of a 2^ per cent, suspension of sheep corpuscles 

 and increasing amounts of the above dilution of rabbit serum (must be fresh not 

 over twelve hours old) as follows: 0.4, 0.8, 1, and 2 c.c.; add sufficient salt solution. 

 Shake and incubate for one hour. 



(a) Has hemolysis occurred? 



(b) How do you explain the reaction? 



(c) From where was the complement derived? 



(d) Are complements found in the bloods of all animals? 



(e) Discuss the question of the multiplicity of complements. 



59 



