Effects of Recombinant Interleukin‐3 and Recombinant Interleukin‐6 on Radiation Survival of Normal Human Bone Marrow Progenitor Cells

The effects of recombinant interleukin-6 (rIL-6) and rIL-3 on the radiation responses of myeloid [colony forming unit-granulocyte-macrophage (CFU-GM)] and erythroid [burst forming unit-erythroid (BFU-E)] human pediatric bone marrow progenitor cells were analyzed. Cytokine exposure times of 30 min, 1 hr, 2 hr, 4 hr, 16 hr, and 24 hr were used prior to irradiation. The most notable observations were based on short exposure data, which provided unprecedented evidence that rIL-6 increases the radiation damage repair capacity of both CFU-GM and BFU-E without affecting their radiation sensitivity, whereas rIL-3 modulated the radiation responses of CFU-GM only. The cytokine-induced increase in radiation survival of CFU-GM or BFU-E at doses ≤200 cGy appeared to be primarily due to an increase in the ability of these hematopoietic progenitor cell populations to repair sublethal radiation damage.