THEORIES OF ANTIBODY PRODUCTION 



mechanism might be visuaHzed in the fashion discussed by 

 Burnet (1956) and by Schweet and Owen (1957). At the 

 present time, however, there seems no reason to engraft 

 such a grossly Lamarckian quaUfication on what might be 

 described as a strictly Darwinian process at the cellular level. 



7. Cellular reactivity required by a clonal selection theory 



The mechanism by which contact with antigen can influence 

 a cell of the corresponding clone must probably be sought 

 from analogies with the various results that have been 

 described by which antigen-antibody reaction will damage 

 cells. The classic examples are immune haemolysis and the 

 anaphylactic response. Haemolysis requires complement and 

 in the classical demonstration of anaphylaxis by the Schultz- 

 Dale procedure no addition of complement is necessary, 

 though Becker (1957) feels that the presence of adsorbed 

 complement on the reacting cells cannot be excluded. None 

 of the reactions is yet adequately understood but it appears 

 to be a valid generalization that reaction of antibody with 

 antigen either incorporated in or attached to the cell surface 

 initiates a process leading to some breakdown in the integrity 

 of the cell surface with leakage of cell contents. In general 

 the character of the response will depend on the type of cell; 

 red cells can show virtually only haemolysis, mast cells 

 liberate heparin, serotonin and histamine, while it seems 

 likely that other mesenchymal cells may suffer damage of 

 various degree up to necrosis. It seems likely that paren- 

 chymal cells are not affected directly by antigen-antibody 

 reaction but only by the pharmacologically active agents 

 liberated by the more generalized mesenchymal cells. 



It is known that immunological reactivity can vary widely 

 according to such factors as the age of the subject, the degree 

 of exposure to antigen and the level of circulating steroid 

 hormones. There is therefore no reason against the postulate 

 that the type of reactivity changes characteristically with 

 maturation of the body in the immunological sense. All that 



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