HOMEOSTATIC MECHANISM 



destructive contact. If the local concentration is very high, 

 for example by there being a substantial deposit with 

 adjuvant in the drainage area, then one might expect the 

 adjacent lymph node to show no antibody production while 

 distant lymph nodes were highly active. This is precisely 

 what Askonas and White (1956) found in their locally 

 immunized guinea-pigs. 



Finally there is the question to be considered of the way 

 such a mechanism could break down in pathological con- 

 ditions. If a lymph node, or equivalent structure such as the 

 tonsil or some of the lymphoid accumulations in the intestinal 

 tract, is subject to some particular type of infection, strepto- 

 coccal or due to the agents of infectious mononucleosis or 

 atypical pneumonia, possibilities arise that in that situation 

 the infection, by enzymic action or otherwise, nearly elimi- 

 nates one or more of the significant body determinants. If 

 a mutant reacting with such a determinant should arise it 

 may be stimulated to proliferate much in the way that a cell 

 competent to react with a foreign antigenic determinant 

 might. Only when cells of a clone so developed leave the 

 centre will they have opportunity of reacting with the deter- 

 minant and they will now by hypothesis have passed beyond 

 the hypersusceptible state. In this type of anomaly the 

 forbidden clones can only be produced in a centre modified 

 by infection. Once the infection is eliminated they will 

 rapidly disappear. 



The nature of the longer-lasting abnormalities is obscure 

 but in general one would expect them to be more directly 

 dependent on the nature of the mutation itself. In another 

 section it is pointed out that one type of somatic mutation in 

 mesenchymal cells appears to result in a near-malignant 

 clone of plasma cells (multiple myelomatosis) in which the 

 physiological phase is stabilized. One can assume therefore 

 that there could exist mutants in which the normal cycle of 

 susceptibility on activation was modified in one way or 

 another. In any given instance it would be necessary to know 



147 10-2 



