IL-1 is important for the thermally mediated increase in neutrophil numbers after TBI. Cell lysates from the intestine of C57BL/6 mice that received either 3 Gy (A,C) or 6 Gy (B,D) TBI with or without heat treatment were collected, and ELISAs were performed using 50 μg lysate per well to determine concentrations of IL-1β (A-B) or IL-1α (C-D). (E) Blocking IL-1 activity with rmIL-1Ra (given immediately before 3 Gy TBI and again every 12 hours for 3 days) reduces the effect of heating. Ly6G+ cell counts were performed on mice that received saline (solid bars) or rmIL-1Ra (hatched bars) in no treatment, TBI alone and TBI + heat groups. Each graph is a representative of at least 2 Ly6G⁺ cell counts were performed on mice that received rmIL-1Ra immediately before 3 Gy TBI separate experiments. n = 5 mice per group. *P < .03, TBI alone group vs TBI followed by heat treatment. †P < .04, TBI + heat group vs TBI + heat + rmIL-1Ra group. n.d. indicates not detected.