266 



INFECTION AND IMMUNITY 



Noguchi l has pointed out very clearly the dangers of not delicately 

 adjusting the quantity of amboceptor used in the reaction. He calls 

 attention to the experiments of Morgenroth and Sachs 2 who have 

 shown that the relationship between complement and amboceptor 

 necessary for hemolytic reactions is one of inverse proportions. In 

 their own words, "in the presence of larger quantities of amboceptor, 

 smaller quantities of complement suffice," and vice versa. Noguchi, 

 in his work, has found that, while in the presence of one unit of ambo- 

 ceptor, 0.1 c.c. of guinea-pig's complement is required to produce 

 hemolysis, by using four, eight, and twenty units of amboceptor, com- 

 plete hemolysis is obtainable with one-third, one-fifth, and one-tenth 

 of the 0.1 c.c. of complement, respectively. For .this reason an excess 

 of amboceptor might result in complete hemolysis in a test, if a small 

 fraction of the complement were left unfixed by the syphilitic antibody. 

 Another result of an excess of amboceptor would consist in a -partial 

 dissociation of the complement from its combination with the antigen- 

 antibody compound. As Noguchi puts it, "a quantity of syphilitic 

 antibody just sufficient to fix 0.1 c.c. of the complement against two 

 units of the amboceptor is no longer efficient in holding back the com- 

 plement from partial liberation against the influence exerted by more 

 than four units of the amboceptor." 



From these considerations it follows that the serum from rabbits 

 immunized against sheep corpuscles must, in each case, be titrated in 

 order to determine the hemolytic unit. For this purpose a number of 

 mixtures are made in test tubes, containing each 0.1 c.c. of complement 

 (fresh guinea-pig serum), 1 c.c. of a 5 per cent emulsion of sheep's cor- 

 puscles, and diminishing quantities of the inactivated hemolytic serum, 

 thus: 



1 Noguchi, Proc. Soc. for Exper. Biol. and Med., VI, 3, 1909. 



2 Morgenroth und Sachs, in Ehrlich's "Gesammelte Arbeiten," etc., Berlin, 1904. 



3 In each tube the volume of the mixture should be made up to 5 c.c. with 0.85 

 per cent salt solution. 



