20 FELIX HAUROWITZ 



formed antibody are related to each other hke punch and coin. According to 

 this view, each antigen molecule can act repeatedly as a template, and thus 

 can induce the formation of numerous antibody molecules. Although this view 

 seems reasonable to chemists, serious objections have been raised by immunolo- 

 gists. These objections have been formulated very clearly by Burnet (1949). 



Burnet bases his objections on the well established fact that antibody for- 

 mation, in some instances, continues over many years or during the whole 

 life. Burnet considers it as impossible that molecules of protein antigens can 

 persist such a long period of time in the sensitized organism. He assumes that 

 the injection of an antigen elicits the production of antibody-forming enzymes 

 and that antibody formation goes on after elimination of all of the antigen. 

 If this view were right, we would have to postulate the formation of enzymes 

 which are able to produce antibodies to strange artifacts of the chemical lab- 

 oratory such as azophenylarsonate or azophenylsulfonate groups. Burnet ad- 

 mits that this is hardly possible. He assumes that in these instances antibody 

 formation proceeds by means of another mechanism for which he has no satis- 

 factory explanation. 



Both the template theory and Burnet's theory agree that the antibody 

 molecule is complementarily adjusted to the determinant group (hapten) of 

 the antigen molecule and that this adjustment takes place during the enzy- 

 matic synthesis of the antibody molecule from amino acids. According to the 

 template theory, the presence of the hapten portion of the antigen molecule 

 is indispensable during the formation of antibody; it remains undecided whether 

 the hapten is present in the unchanged antigen molecule or whether it is incor- 

 porated into the synthesizing enzyme or other molecules of the antibody-form- 

 ing cells. In contradiction to these views, Burnet postulates continued anti- 

 body formation after elimination of all of the antigens. 



The reason why I discuss Burnet's view so extensively is that many, if not 

 most, immunologists are inclined to accept it, or to "combine" it somehow 

 with the template theory. Such proposals of combination are based on a mis- 

 understanding of the basic ideas of the two theories. One of them postulates 

 the presence of the antigen (or its hapten), the other absence of the antigen 

 during the enzymatic process of antibody synthesis. I do not see how these 

 two postulates can be combined. 



The attractiveness of Burnet's theory for bacteriologists and serologists is 

 due to the particulate nature of most of the pathogenic antigens. There is no 

 doubt that bacteria disappear rapidly from the organism. This does not mean, 

 however, that the true antigens, i.e., their antigenic molecules, disappear. It 

 has been shown very impressively by Felton (1949) that pneumococcal poly- 

 saccharides, injected into mice, persist there for many months if not for years. 

 Similarly, INlcIMaster et al, (1955), using serological methods, have proved 

 the persistence of protein antigens. This persistence of antigens is the principal 



