ANTIBODIES II 



NH2 NH2 NH. 



Antigen 

 containing 



JSO3H 1^ JA3O3H2 ^ JCOOH 



SO-jH 



Metanilic acid w-Aminoarsonic ;w-Aminobenzoic Sulfanilic Aniline 

 acid acid acid 



Strength of ^ q 



reaction ^^=^ ^ ± = u 



Fig. 2-1. Reaction of antiserum for metanilic acid (Landsteiner, 1945). 



with a protein coupled with one of the cross-reacting haptens vmtil 

 no further reaction takes place, then testing the treated antiserum with 

 the homologous and other related haptens. In order to avoid having 

 soluble complexes of antibody and antigen left in the mixture, the 

 anti-metanilic serum may be treated with haptens coupled to the 

 insoluble structures (stromata) left after lysis of red blood cells and 

 removal of the hemoglobin. A serum which has been thus treated 

 to remove all the antibody which will react with a given antigen is 

 said to have been absorbed with that antigen. The results of such an 

 experiment (Landsteiner and van der Scheer, 1936) are shown in 

 Fig. 2-2. 



It can be seen that in each case absorption with heterologous 

 hapten-protein compound, to the point of reducing the reaction with 

 that hapten to zero, leaves considerable precipitating power for 

 antigens containing the homologous hapten. Generally, it also leaves 

 some reactivity for other heterologous haptens. Each hapten, evi- 

 dently, combines with that fraction of the antibody molecules for 

 which it has the highest affinity. The majority of the antibody mole- 

 cules react best with the homologous hapten, most of which is left 

 after heterologous absorption. 



Similar results were obtained by Hooker and Boyd (1934) and 

 Landsteiner and van der Scheer (1940) with egg albumins of vari- 

 ous species, although here the exact nature of the chemical similari- 

 ties which led to cross-reaction was not known. 



From these and similar experiments (Landsteiner and van der 

 Scheer (1936) drew the conclusion that "antibodies formed in re- 

 sponse to one antigen, although adjusted to a certain structure, are not 

 entirely uniform but vary in specificity to some degree." Boyd (1943) 



