SERIAL TRANSPLANTATION OF HAEMATOPOIETIC 

 TISSUE IN IRRADIATED HOSTS 



P. C. ROLLER AND S. M. A. DOAK 

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



INTRODUCTION 



Ionizing radiation as a cause of murine leukaemia have been demonstrated in 

 numerous experiments, (Furth and Furth, 1936; Kaplan, 1947; Mole, 1958), 

 in which the cells, tissues and organs involved in the leukaemogenic process 

 have been directly exposed to radiation. It has also been established that non- 

 irradiated thymuses, when grafted into irradiated thymectomized isogenic 

 mice of certain genetic constitution, may develop into thymic lympho- 

 sarcomas (Kaplan et al., 1953, 1956; Barnes et al., 1959). More recently it has 

 been found that many leukaemias, which arose in allogenic mouse chimaeras, 

 were of donor origin (Uphoff and Law, in press). In these instances the malig- 

 nant transformation involved cells, themselves non-irradiated, but which 

 were transplanted into irradiated hosts. From these experiments it appears 

 that the irradiated host environment has had a leukaemogenic effect upon 

 the non-irradiated donor cells. In both these cases, however, the possibility 

 that the effect observed is in no way related to irradiation, but simply due to 

 some "infective" prmciple, must not be ignored. 



In order to clarify the issue, experiments were designed to investigate the 

 possibility of inducing leukaemia following the serial passage of marrow cells 

 into isogenic hosts, the latter having been exposed previously to a lethal 

 radiation dose which destroyed the host haematopoietic tissues. It is argued, 

 that such a procedure would cause a hyperactivity in the donated haemato- 

 poietic tissue and that this hyperactivity, if continued, might result in 

 leukaemia. 



METHODS 



A group of 30 C3II/Bi mice were given 650 r (LDgg) and 24 hr later 

 each mouse received an injection of bone-marrow (cell dose 4 x 10^) from 

 non-irradiated C3H donors. After 28 days the marrow from six of the primary 

 isogenic chimaeras was used as donor tissue for injection into a second group 

 of 30 irradiated hosts, thus making secondary chimaeras. After another 28 

 days, this procedure was repeated when six secondary hosts were sacrificed 



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