CELLULAR REACTIVITY REQUIRED 



The combination of frequent minor mutation and a 

 highly effective selective process would rapidly improve the 

 accuracy of the complementary relationship to new antigenic 

 determinants. The final distribution of patterned globulin 

 molecules in the adult animal would on this view come to 

 be almost wholly determined by the immunological history 

 of the individual. Such a view would provide opportunity 

 for many functional variations depending (a) on the com- 

 pleteness or otherwise of the initial complement of prototype 

 clones, something which might well be determined by the 

 genetic make-up of the individual; (b) on changing capacity 

 to mutate with advancing age. It may be relevant that 

 Sabin et al. (1947) found that elderly Japanese men produced 

 an antibody against Japanese encephalitis B vaccine only if 

 they had evidence of past infection by the virus. 



8. Summary 



The clonal selection theory of antibody production is based 

 on the concept that the antibody-producing cells of the body 

 form part of a mobile population of mesenchymal cells 

 constantly undergoing physiological and mutational change. 



When mutational change occurs a new clone is initiated. 

 It is postulated that mesenchymal cells carry surface sites 

 analogous to the specific patterns on the antibody globulins 

 they produce. Stimulation by contact of these sites with the 

 corresponding antigenic determinant may provoke more 

 than one type of response, but the crucial one is the prolifera- 

 tive response which allows a selective advantage to the clone 

 concerned. 



The theory differs from the standard interpretation of 

 antibody production in replacing the concept that in one way 

 or another the antigen actively enforces production of a new 

 pattern of specific globulin, by the view that somatic muta- 

 tion and selection within the mesenchymal cell population 

 can have the same overall effect. 



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