THEORIES OF ANTIBODY PRODUCTION 



Jerne's theory in its original form is inadmissible until it has 

 been provided with a cellular basis. It then becomes identical 

 with the clonal selection hypothesis (theory 5) . The common 

 feature of the two 'biological' approaches, the indirect 

 template hypothesis (3) and the clonal selection hypothesis 

 (5), is that once antibody-producing capacity is implanted 

 in a clone, cells of that clone respond by activation and pro- 

 liferation when they have new contact with the appropriate 

 antigen. This provides an evolutionary situation within 

 which clones will wax and wane in size and activity in ways 

 analogous to a mixture of bacterial clones in a common but 

 changing environment. 



A direct comparison between the indirect template theory 

 and the clonal selection theory is more difficult than at first 

 sight would seem likely. Once a potential antibody- 

 producing cell has been modified by the antigen so that it can 

 give rise to antibody-producing descendants, we have a 

 clonal situation even with the indirect template theory. The 

 only essential difference between theories (3) and (5) is 

 simply the origin of the primary specific patterns. In the 

 clonal selection theory (5) they are pre-existent as a result 

 of processes of embryonic development. The indirect tem- 

 plate theory (3) gives each macrophage an inbuilt and 

 somatically inheritable recognition mechanism which allows 

 it to recognize and inactivate body components, perhaps by 

 breaking them down into inert small molecular fragments. 

 Unrecognized (foreign) macromolecules pass to the nucleus 

 and induce genetic modification. The modified character is 

 then passed to a cell of the lymphoid series, either by some 

 mechanism resembling transduction or by actual conversion 

 of the modified cell to a lymphoid stem cell. 



Perhaps the best way to summarize the position is to say 

 that there are two sets of observable phenomena which are 

 crucial to the understanding of antibody production. 



(i) The non-antigenicity of body components and the 

 phenomena of prenatally induced tolerance. 



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