PERIPHERAL BLOOD STUDIES UPON SOME ISOGENIC 



CHIMAERAS 



A. J. S. DAVIES, ANNE M. CROSS, and P. C. ROLLER 



Chester Beatty Research Institute, Institute of Cancer Research^ London, 



England 



The successful use of tissue therapy after total-body irradiation (Lorenz et al., 

 1952) and the fact that success is commonly due to the inception of a chunaeric 

 state (Lindsley et al., 1955) are now well-known. There remain, however, 

 many problems both from an experimental and an applied viewpoint (KoUer 

 et al., 1961). Experimentally, though we know most of the factors which 

 determine the establishment of chimaerism, we know little of the details of 

 the process. 



In the present study the dose of radiation to the host animal and the 

 number of cells injected therapeutically within 24 hours after irradiation have 

 been systematically varied. Survival and speed of recovery of haematopoiesis, 

 as assessed by peripheral blood counts, have been measured. Inbred BALB/C 

 strain mice were used throughout. For these animals the LD5Q 30 days is 

 about 620 r, the LD99 about 700 r. 



Table I. The survival and peripheral blood values {as percentages of control) of 



BALB/C mice 10 days after various doses of total-body irradiation followed or 



not by intravenous injection of 10' isogenic bone-marrow cells 



The effect of marrow therapy upon survival and peripheral blood counts 

 is illustrated in Table I. It is noteworthy that the depression of aU elements of 

 the peripheral blood was proportional to the dose of irradiation and that in all 



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