204 MORTEN SIMONSEN 



members of different clones. Clone I is supposed to possess all 

 genes necessary for production of antibodies to all 4 antigens. 

 Clone II has lost genes necessary for reaction to AKR antigen, 

 while clones III and IV represent further losses. Reactivity to 

 DBA/ 2 antigen, however, remains intact even in clone IV. 



If the C3H mouse (being the owner of all these clones) is 

 injected with DBA/ 2 antigen, there is no reason why one clone 

 would be stimulated to proliferate more than the others. The 

 percentage of cells with affinity to DBA/2 would of course remain 

 at 100 as it was before stimulation, and the small increase in the 

 F.I. (to about I • 8) could be ascribable to a higher reactivity per 

 ceU. 



The extreme alternative situation is the one in which AKR 

 antigen is injected (as supposed in Fig. 2). In this case only clone I 

 could be stimulated. The proliferation which this would lead to, 

 would raise the percentage of cells with affinity to AKR (pre- 

 sumably even more so if hyperimmunization was continued). 

 As the result of proHferation of clone I, it would also be expected 

 that reactivity to facultative antigens other than AKR would be 

 increased at the same time if the genes which determined 

 reactivity towards them happened to be present in the same clone. 

 This would in fact be a possible mechanism for "non-specific" 

 stimulation of immunological defence reactions, as opposed to 

 that which results when there is a sharing of common antigens. 



The main purpose of Fig. 2 is, however, merely to illustrate the 

 notion that different rates of mutational losses in different loci of 

 immunologically competent cells will lead to different proportions 

 between clones when they are stimulated by their corresponding 

 antigens. 



It may be of significance in this context that the total number of 

 spleen cells recovered from the hyperimmunized C3H spleens, 

 as compared to normal C3H spleens (Table II, column 4), was, on 

 the average, increased much more after injection with AKR 

 antigen than after any of the other antigens. The donors which 



