IL-15 ADMINISTRATION FOLLOWING SYNGENEIC BONE-MARROW TRANSPLANTATION PROLONGS SURVIVAL OF LYMPHOMA BEARING MICE

The toxicity and antitumor efficacy of simian IL-15 was compared with human IL-2 in the context of syngeneic BMT. Groups of mice receiving o r not receiving anti-CD3 activated splenocytes, termed ''T-activated k iller'' (T-AK) cells, were treated between days 7 and 12 with escalati ng doses of IL-2 or IL-15 given twice daily. Recipients of IL-2+T-AK o r IL-15+T-AK had significantly higher survival rates than saline+T-AK. Tissues from IL-2+T-AK, but not IL-15+T-AK, treated mice revealed the presence of perivascular infiltrates in the lung and liver consisting of CD8(+) T cells and Mac-1(+) cells. Our findings demonstrate that I L-15 can be used effectively to stimulate antitumor responses post-BMT and may be associated with less toxicity than IL-2.