Analysis of minocycline as a countermeasure against acute radiation syndrome

Background/Aim: To evaluate the impact of an antibiotic, minocycline, on several immune parameters in response to radiation in a mouse model. Materials and Methods: C57BL/6 mice were treated with minocycline (i.p.) for 5 days, beginning immediately before radiation with 1-3 Gy ⁶⁰Co γ-rays. Spleen and blood were collected on day 4 post-irradiation. Cell populations were determined in the blood and spleen. Splenocytes were activated with anti-CD3 antibody for 48 h and cytokines were quantified. Results: Minocycline increased the counts and/or percentages of splenic macrophages, granulocytes, natural killer, T- and CD8⁺ T-cells (p<0.05 versus radiation alone). Minocycline significantly increased the expression of interleukin-1α and β, which are radioprotective, as well as the ones of granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor, which accelerate neutrophil recovery (p<0.05 versus radiation alone), while suppressing cytokines that could prevent hematopoiesis, e.g. macrophage inflammatory protein-1α, tumor necrosis factor- α and interferon-γ. Conclusion: These data indicate that minocycline should be further tested for use in restoration of the hematopoietic system after radiation exposure.