9 



IMMUNE SERA 



necessary factors is bound and prevented from 

 acting. l 



The action of anticomplements is specific, i.e., an 

 anticomplement combines only with its specific 

 complement. Thus an anticomplement serum 

 derived from rabbits by treatment with guinea- 

 pig serum combines only with the complement of 

 normal guinea-pig serum, not, however, with the 

 complements of other animals. Exceptions to this 

 are those cases in which the complement of the 

 other species possess receptors identical with those 

 of the first. 



In order that a normal serum of species A, 

 injected into species B, produce anticomplements 

 there, the side-chain theory demands that the com- 

 plements of A find fitting receptors in species B. 

 According to Ehrlich, however, normal serum con- 

 tains many different complements and not merely a 

 single one. Under the circumstances, it is easily 

 possible that only a few of the complements in the 

 serum of A find fitting receptors in species B. We 

 shall then obtain an anticomplement serum which 

 inhibits the action of some, but not of all the com- 

 plements of species A. Thus it might inhibit the 



1 By treating animals with normal sera of certain other 

 species, it is possible to produce not only anti-complements, 

 but also specific anti-bodies against certain other constituents 

 of normal serum. These are, for example, anti-agglutinins, 

 which inhibit the action of the haemagglutinins of normal serum, 

 and anti-precipitins, which we shall discuss later. 



