MODIFICATION OF RUNT DISEASE 351 



have accordingly elected to use the simple quantity of total body 

 weight as an overall estimate of the progress being made by the 

 diseased animal. This criterion is, of course, readily supplemented 

 by observations of the incidence of disease and the time of death 

 where applicable. A preliminary report of our use of the v/eight- 

 gain method has previously appeared (Russell, i960) and is 

 amphfied by the present communication. This method has also 

 been used by Anderson, Delorme and Woodruff (i960). 



Plan of experiments 



The experiments were divided into three parts. First, the course 

 of runt disease as exhibited by the present strain combination of 

 mice, DBA/ 1 donors and C57BL/6 recipients, was determined 

 along with some of its pathological features. The importance of 

 the dose of foreign cells injected was investigated and some 

 information was gained as to the effect of delivering the injection 

 by different routes. 



Secondly, efforts were made to influence the otherwise virtually 

 inevitable course of the disease by methods designed to specifically 

 inactivate or destroy the foreign lymphoid cell inoculum. Two 

 types of treatment were used here : 



(i) A second injection of spleen cells was given from adult 

 donors isogenic with the neonatal recipients, administered either 

 by mixing the isologous cells with the homologous cell suspension 

 before injection, by separate administration immediately after the 

 homologous spleen cells via another vein, or by delaying the 

 second injection for varying periods after the first. Second injec- 

 tions of cells from animals previously sensitized to DBA/ 1 tissue 

 by skin grafting were also used. 



(2) Secondary injections of serum were given from animals 

 sensitized to the original donor strain (DBA/i) either by skin 

 grafting or by injections of spleen cells with an adjuvant mixture 

 in the foot pads, as detailed below. 



