Deregulation of endogenous IL-15 increases the mortality and morbidity from acute GVHD. B6 or B6D2F1 mice received transplants of 5 × 106 wt B6 splenic T cells and 1 × 107 BM cells from either wt B6 or IL-15 tg B6 mice. (A) Survival of wt B6D2F1 mice receiving IL-15 tg B6 allogeneic (IL-15 tg allo, •,n = 12) or wt B6 allogeneic BM cells (wt allo, ▪, n = 15); P = .0004. Survival of wt B6 mice receiving IL-15 tg B6 syngeneic (IL-15 tg syn, ○, n = 7) or wt B6 syngeneic (wt syn, □, n = 7) BM cells. Data represent combined results from 2 independent experiments. (B-C) Mice from each group described in panel A were weighed and scored for clinical GVHD as described in “Materials and methods.” Data are representative of results (mean ± SE) from 2 similar experiments. (D) Upper panel: IL-15 transgene expression in bone marrow of recipients of IL-15 tg B6 allogeneic BM cells. Positive control (+) cDNA was prepared from a known IL-15 tg B6 mouse, and negative control cDNA (-) was prepared from a wt B6 mouse. Lower panel: sample integrity was established by polymerase chain reaction (PCR) amplification of 18s cDNA.
