Infections remain a serious problem following injury. Immune modulation offers an additional strategy for the treatment of infections. We evaluated the ability of a multilineage hematopoietic growth factor, granulocyte-macrophage colony-stimulating factor (GM-CSF), to improve survival following burn injury with a superimposed burn wound infection. Groups of 12 BDF1 mice received a 15% total body surface area (TBSA) thermal injury by immersion in 100 degrees C water; 6 x 10(3) Pseudomonas was then applied to the burn wound. The GM-CSF was injected subcutaneously B.I.D. for 7 days. Mice receiving the 10-ng dose of GM-CSF had significantly improved survival compared with the controls; other doses had no significant effect on survival. Clinical trials to assess the ability of GM-CSF to reduce infectious complications following burn injury are underway and these data suggest selecting a specific dose may be critical in achieving maximal benefit.