LEUKAKMIA TRKAll.l) \>,\ KADI A I ION 



Table I . Animals surviving (a) and dying (f) after treatment with subacute whole-body 

 X-irradiation and intravenous bone marrow 



S.C. = Subcutaneously. I.V. = Intraxenuusly 



* Deaths not attributable to leukaemia. 



One of them has been nominated 151/2 and, although its origins are a little 

 obscure, in our opinion it was a spontaneous leukaemia occurring in a CBA 

 mouse; 137/1 was another leukaemia of the CBA strain l)ut was induced by 

 radiation; 251 rose in an isologous chimaera, an irradiated CBA mouse 

 restored by our colleague, Miss C. L. Miller, with liver from a normal CBA 

 foetus; 138/2, on the other hand, was induced by X-rays in a C57BL 

 mouse. 



Secondly, observations of the mice in the first three experiments, of which 

 you have seen the preliminary results, over long periods of time until their 

 death, has confirmed that three months is a sufficiently long time for one to 

 be able to assess the success or failure of the therapy as far as cure of the 

 leukaemia is concerned. There was no recurrence of leukaemia after this 

 time. Most of the mice in these groups lived for between one and two years 

 after treatment and died apparently of old age, perhaps rather accelerated 

 by the irradiation. 



Thirdly, few of the subsequent repetitions were as successful as the first 

 three. Table 2 summarizes the results of those experiments in which CBA 

 mice had originally been injected subcutaneously with 10® cells of leukaemia 

 151/1: it indicates that long-term survivors were obtained following the 

 irradiation witli 1620 rad over 25 hours and restoration with both isologous 

 and homologous bone marrow. During this period between Experiments 

 I and VII, the generation of passage of 151/1 extended from the sixth to the 

 13th. Table 3 shows that the final results were less successful when the 

 leukaemia 151/1 had been injected intravenously. A variable number 

 of successes were obtained up to Experiment \', where the leukaemia 

 was in its ninth passage; but in Experiment Mil, with the leukaemia 

 in its 13th passage, and in subsequent trials, no successes were 



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