Sublethal Gamma Irradiation Increases IL-lα,IL-6,and TNF-α mRNA Levels in Murine Hematopoietic Tissues

The effects of sublethal (7.75 Gy) ⁶⁰Co gamma radiation exposure on endogenous bone marrow and splenic interleukin-1α (IL-lα), IL-6, and tumor necrosis factor-α (TNF-α) mRNA and protein levels were assayed in B₆D₂F₁ female mice. Bone marrow and spleen were harvested from normal and irradiated mice on days 2, 4, 7, 10, and 14 postexposure, and cytokine mRNA levels were determined by reverse transcription polymerase chain reaction (RT-PCR) and Southern blot analysis. IL-lα mRNA levels were significantly increased in bone marrow at days 2 and 4 postirradiation and at day 7 in spleen compared with controls. Postirradiation IL-6 mRNA levels showed a significant increase at day 2 in bone marrow and at days 7 and 10 in spleen. TNF-α mRNA levels exhibited a significant increase at day 2 postirradiation in bone marrow, but in spleen no difference between control and irradiated samples was observed on any day postirradiation. Interestingly, there were no significant differences in the cytokine protein levels in postirradiation bone marrow, spleen, or serum when compared with normal controls.