First, we transplanted purified CLL cells from 20 different patients into 30 mice conditioned with HS5-CD40L-IL4 cells (21 mice with 1 scaffold, 4 mice with 2 scaffolds-both flanks, 5 mice with only i.p. HS5-CD40L-IL4 [no scaffold]) (Supplementary Table 2). This evidence concerns the gene IL4 and B-cell chronic lymphocytic leukemia.