The odds of mice surviving radiation sickness are improved by antibiotic treatment, and increased further by boosting an immune-system protein.

Eva Guinan of Harvard Medical School in Boston, Massachusetts, and her colleagues exposed mice to 7 grays of radiation. This dose killed all but 5% of untreated mice within 30 days. Alone, upping levels of the protein BPI — which neutralizes certain bacterial toxins — had no measurable effect on mouse survival, whereas a regime of just fluoroquinolone antibiotics increased the survival rate to 40%. However, around 75% of mice given both antibiotics and a BPI boost survived, and these animals also recovered more bone-marrow cells than those given antibiotics alone.

Combination treatment helped mice that were treated up to 24 hours after radiation exposure; most existing treatments for radiation sickness must be taken before or within hours of exposure.

Sci. Transl. Med. 3, 110ra118 (2011)