352 PAUL S. RUSSELL 



Thirdly, several treatments of a non-specific type which might be 

 expected to interfere with the immunological reactivity of the 

 injected lymphoid cells were tested. These were as follows: 



(i) a series of injections of cortisone acetate (0-025 mg./g. 

 body weight) ; 



(2) a single exposure to whole-body X-irradiation two to five 

 days after the spleen cell injection. 



A short course of treatment with each of two antimetabolic 

 drugs has also been tried. 



(3) Burroughs- Wellcome 57-322* was selected as one of a 

 group of the drugs which act on nucleic acid metabolism by 

 competitive inhibition of purines. 



(4) Amethopterin (methotrexate) was chosen as an example of 

 an antifolic acid compound. 



Finally, a few preliminary attempts to achieve the secondary 

 transfer or passage of runt disease have been made. As stated 

 above, almost all experiments have included the dual purpose of 

 evaluating not only the impact of the injected cells upon their 

 recipients but also, whenever the animals lived, of testing the 

 specific effect of the foreign cells, under the conditions of the 

 particular experiment, on the host's ability to react to tissues of 

 donor origin by observing the behaviour of a graft of donor 

 strain skin. 



Materials and Methods 



Animals 



Mice of highly inbred strains were used throughout. C57BL/6 

 neonatal animals were employed as recipients and DBA/ 1 adults 

 of both sexes as spleen cells donors, f These strains differ 



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

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



•f Both strains were obtained from the Roscoe B.Jackson Memorial Laboratory 

 in Bar Harbor, Maine, and were maintained by a system of pedigreed matings as 

 inbred stock in such a way as to minimize the development of separate subHnes 

 within the colony. 



