242 INFECTION AND IMMUNITY 



FURTHER FACTS AND THEORIES CONCERNING ANTIBODIES 

 AND COMPLEMENT 



Multiplicity of Amboceptors. Fresh normal serum, as Nuttall 1 was 

 first to show, possesses moderate bactericidal powers which are lost 

 when the serum is subjected to heat. Since such inactivated normal 

 serum can be reactivated by the addition of fresh peritoneal exudates, 2 

 it is plain that the bactericidal power of normal serum must depend, 

 like that of immune serum, upon amboceptor and complement. But 

 normal serum often exerts lytic powers upon several species of bacteria, 

 or, in the case of hemolytic tests, upon the red blood cells of several 

 species of animals. It is supposed that this multiplicity of action is 

 due to the presence in the normal serum of a variety of different ambo- 

 ceptors or immune bodies. The method for proving this was devised 

 by Ehrlich and Morgenroth. 3 They worked with normal goat's serum, 

 which has the power of hemolyzing the red blood cells of guinea-pigs 

 as well as those of rabbits. Goat serum, inactivated by heat, was 

 mixed with rabbits' corpuscles. After the mixture had been allowed 

 to stand for a short time, the corpuscles were removed by centrifugali- 

 zation. The serum was then reactivated and found still to possess its 

 hemolytic power for guinea-pigs' blood, but to have lost this power for 

 rabbits' blood. By a similar technique, Pfeiffer and Friedberger 4 were 

 able to demonstrate the multiplicity of bactericidal immune bodies in 

 normal sera. 



The immunity acquired by an animal as the result of treatment with 

 any of the various antigens is specific. An animal immunized against 

 the cholera vibrio, for instance, possesses marked bactericidal powers 

 for the cholera vibrio only. 



The essential fact to be remembered is that the amboceptor or im- 

 mune body alpne enters into direct relation with the substance used for 

 immunization, and the specificity of immune sera therefore depends en- 

 tirely upon the increase of amboceptor or immune body. 



Von Dungern, 5 indeed, was able to show that though specific ambo- 

 ceptor was increased as immunity was acquired, there was no corre- 

 sponding enhancement of the complement. The chief difference be- 

 tween a normal and an immune serum in this respect, therefore, con- 

 sists in an enormous increase, in the latter, of the specific amboceptor. 



1 Nuttall, loc. cit. 2 Moxter, Cent, f . Bakt., xxvi, 1896. 



3 Ehrlich und Morgenroth, Berl. klin. Woch., 1901. 



4 Pfeiffer und Fricdberger, Deut. med. Woch., 1901. 

 8 v. Dungern, Miinch. med. Woch., xx, 1900. 



