M. KENT 



Table 1. Length of homograft sui\i\al in ral)t)its irradiated 

 prior to skin grafiintj 



^ ^ Number of r^ ,, Graft survival in days 



Grout) LL-. Deallis . -' t, 



^ rabbits Average Range 



14 days. It will be seen that 900 r has been established as a lethal X-ray 

 dosage with the techniques being used. A control value of 9-5 days has 

 been reached for homograft survival. The increasing X-ray dosages have 

 been accompanied by a lengthening of homograft survival. The wide range 

 of variation in homograft survival in the irradiated groups is indicated. 



REFERENCES 



1 Dempster. W.J. Brit. med. J. it (1951) 1041 



2BILLINGHAM, R. E.. Brent, L. and Medawar, P. B. Phil. Trans. B 239 (1956) 357 



^Dempster, W. J., Lennox, B. and Boag, J. W. Brit. J. exp. Path. 31 (1950) 670 



*CoNGDON, C. C. and Urso, L S. Aryier. J. Path. 33 (1957) 749 



^CoNGDON, C. C. and Urso, L S. Radiation Res. 5 (1956) 474 



^LouTiT, J. F. /. Nuclear Energy 1 (1954) 87 



^Jacobson, L. O. Cancer Res. 12 (1952) 315 



*FoRD, C. E., Hamerton, J. L., Barnes, D. W. H. and Loutit, J. F. Nature, Land. 

 177 (1956) 452 



®Helfinger, M. F., Ferguson, J. H. and Reemenschneider, P. A. /. Lab. din. 

 Med. 4:2 (1953) 581 

 i°Ferrebee, J. W., Lochte, H. L., Jaretzki, A., Sahler, O. P. and Thomas, E. D. 



Surgery 43 (1958) 516 

 "Makindon, T. Proc. Sac. exp. Biol., N.Y. 92 (1956) 174 

 i2Main, J. M. and Prehn, R. T. /. nat. Cancer Inst. 15 (1955) 1023 

 "Trentin, J. Proc. Soc. exp. Biol., N.Y. 92 (1956) 688 



DISCUSSION 



Dr. Loutit : Mr. Kent has asked for guidance, and I suggest that the last line of the 

 table does imply that in his group where 33 per cent survived from 900 r, the 

 immune response has only been temporarily inactivated by this dose. But if he then 

 proceeds to give bone marrow for restoration to a comparable group, it is liable that 

 the bone-marrow graft will only last 29 to 51 days or thereabouts and will then be 

 rejected. I think he should go on with the table to see what is 100 per cent death, 

 and probably, although he will not be able to score the survival of homografts of 

 skin, he should, by means of the technique of marked leukocytes of Vince, George, 

 Rocke and Garvan, be able to score the length of survival of his marrow grafts. 

 Mr. Rocke: Do you have any information on the possible effect of irradiation of the 

 donor before taking the graft on this homograft technique? 

 Mr. Kent: I am sorry, there is no information on that. 



71 



