OBSERVATIONS ON THE EFFECT OF SPLEEN- 

 SHIELDING AND THE INJECTION OF CELL 

 SUSPENSIONS ON SURVIVAL FOLLOWING 



IRRADIATION * 



Leon O. Jacobson, Edna K. Marks and Evelyn O. Gaston 



Department of Medicine and the Argonne Cancer Research Hospital, The University of 



Chicago, Chicago, Illinois 



Our finding that spleen-shielding and spleen or embryo transplants enhance 

 the survival of mice exposed to a lethal amount of total-body X-radiation 

 (1025r) led to some further experiments in which we demonstrated that a 

 suspension of spleen cells injected intraperitoneally also increases the survival 

 of mice exposed to 800 r^'^. This latter observation was confirmed by 

 Cole et aP. Lorenz'* found that the survival of mice exposed to 900 r was 

 significantly increased if the animals were given intravenous injections of 

 bone marrow suspensions after X-irradiation. These findings together with 

 the observations that liver-shielding or the injection of mashed embryo 

 suspensions protected against radiation-induced mortality prompted us to 

 investigate the effectiveness of suspensions of cells from the liver of adult, 

 baby, and embryonic mice. In addition, since the results from some of the 

 experiments varied because the suspensions of cells from the several sources 

 (spleen, bone marrow, and liver) were not standardized, it seemed timely to 

 determine the optimum number of cells from each of these tissues that would 

 provide maximum survival and the minimum number of cells necessary to 

 efifect survival following lethal irradiation. Such information was needed to 

 compare the 'potential' of cells from various tissues and to serve as a baseline 

 for 'cell-type' studies of the various suspensions. 



This report gives the observations that we have made thus far. 



Observations 



Bone marrow — Lorenz'* aspirated bone marrow from four long bones (femora 

 and radii) of mice by means of a 26-gauge hypodermic needle. The marrow 

 was then suspended in buffered saline solution and given intravenously 

 immediately after preparation to an irradiated mouse. We employed this 

 technique in our earlier studies. The amount of marrow obtained under 

 these conditions was found to vary considerably and thus the results were not 

 consistent. 



In the studies reported here, mice that were to receive bone marrow 

 suspensions were exposed to 900 r total-body X-radiation. Bone marrow 

 for the suspensions was obtained from 10- to 12-week-old mice. Saline or 

 Locke's solution was used as the diluent. Cell counts were made according 



* The contents of this paper have also been presented at the meetings of the 5th Inter- 

 national Congress of Hematology, Paris, France, September 6-12, 1954. 



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