MODIFICATION OF RUNT DISEASE 369 



very significantly (P<o-oo5). Cortisone thus has a mild and 

 transient ameliorating effect on runt disease in these mice. 



(2) Wholc-hody X-irradiation. Whole-body irradiation was also 

 tested for its influence on the course of acute runt disease in these 

 neonatal animals before they had reached the "plateau period". 

 Following the standard injection of more than 5 million DBA/i 

 adult spleen cells intravenously on the day of birth, a total of 20 

 C57BL/6 mice were treated at various times with doses of whole- 

 body X-irradiation as follows: 3 received 100 r. on the second day 

 of Hfe; groups of 3 received 50, 100 and 150 r. on the fourth day of 

 life; groups of 4 received 100 and 300 r. on the sixth day of life. 

 (Radiation delivered at 116 r./min. from 50 cm., 250 kv, 15 mA, 

 I • 5 mm. Cu H.V.L.). hi every instance these animals died before 

 non-irradiated animals of the same litter also injected with homo- 

 logous cells. Thus, nothing but a slightly deleterious effect of this 

 treatment is demonstrated with the doses of cells and irradiation 

 chosen. 



(3) Burroughs-Wellcome 57-322* (6-(i-methyl-4-nitro-5-imi- 

 dazolyl)thiopurine). A wide variety of cytotoxic substances 

 have been known for some time to influence the production of 

 antibodies. 



This imidazolyl thiopurine derivative was chosen for testing 

 since it has recently been shown to have a relatively low toxicity at 

 doses which appreciably inhibit the inductive phase of agglutinin 

 formation against sheep erythrocytes in mice (Nathan et aL, 1961). 

 This fmding reinforced similar observations made earlier by 

 Schwartz, Stack and Dameshek (1958) and by Sterzl (i960, 

 1961) that 6-mercaptopurine, and some related compounds, will 

 greatly suppress the inductive phase of antibody production. 



Continuing administration of B.W. 57-322 and 6-mercapto- 

 purine has also recently been found to prolong the survival of 

 renal homografts in dogs (Calne and Murray, 1961) although the 



* Generously supplied by Dr. George H. Hitchings of Burroughs Wellcome 

 Co. (U.S.A.) Inc. 



