MECHANISM OF ANTIBODY FORMATION 85 



Studies in another direction by Landsteiner and his followers have shed 

 considerable light on the role of the "determinant groups" in antigens 

 on the specificity of antibodies. There is though no evidence that the 

 natural simple proteins contain characteristic "determinant groups" to 

 account for the specificity of homologous antibodies; however such 

 groups introduced into the artificial proteins have been shown, by 

 numerous examples, to exercise the power of determining the specificity 

 of antibodies against them. 



Of the considerable number of such examples, which will be taken 

 up in a later chapter on the similarity of the specificities of enzymes 

 and antigens, we will consider at this point only two of the most out- 

 standing examples. It is to be noted that these examples have more or 

 less served as a basis for the theories on the mechanism of antibody 

 formation. Landsteiner and van der Scheer (1928, 1929) demon- 

 strated that d- and l-^^ara-amino-tartranilic acids coupled with proteins 

 produce antibodies specifically reactive. Avery and Goebel (1929) 

 similarly showed that p-amino-phenol-/3-glucoside and p-amino-phenol- 

 /?-galactoside coupled with a protein produce respectively specific anti- 

 bodies. In these examples we have the differences between the "de- 

 terminant groups" reduced to the simplest structural forms known to 

 chemistry. In tartranilic acid antigens the apparent difference is one 

 of optical or space isomerism. In p-amino-phenol-/?-hexoses likewise the 

 difference is one of space isomerism. These differences are associated 

 also with other chemical properties, such as differences in the reactivity 

 to specific enzymes, solubilities, and also physical and chemical dif- 

 ferences of their respective derivatives. How are we then to interpret 

 the specificity of antibodies produced against them? Does it signify 

 that antibody against d-antigen possesses 1-configuration and vice 

 versa? Or are we to assume that antibody against one is the space isomer 

 of the antibody against the other? Or else must we assume that 

 chemical and physical differences resulting from or associated with the 

 difference of optical or space isomerism are responsible for the dif- 

 ferences in the specificities of antibodies against each and every one 

 of them? A satisfactory answer to these questions has an important 

 bearing on the formulation of the concepts of the structure of anti- 

 bodies in relation to the nature and the position of the serologically 

 reactive specific groups. At present our knowledge regarding these 

 questions is not of sufficient scope to formulate the answer satisfactorily; 



