A novel immunosuppressant, deoxyspergualin, given at doses of 2.5 to 20 mg/kg/day on days -3, -2 and -1 before X irradiation protected BALB/c mice from the lethal effects of radiation in a dose-dependent manner. The dose of radiation that killed 50% of the mice within 30 days was 5.63 Gy for mice receiving radiation alone, but was 7.13 Gy in the mice given deoxyspergualin at 20 mg/kg. Prior administration of deoxyspergualin ameliorated leukopenia and thrombocytopenia induced by sublethal irradiation, and significantly increased the number of femoral spleen colony-forming units (CFU-S) that survived irradiation. Deoxyspergualin also reduced the proportion of CFU-S in S phase, as determined by in vitro sensitivity to hydroxyurea. These findings suggest that deoxyspergualin may be effective in the prevention of hematopoietic injury caused by radiotherapy.

Recombinant human interleukin-1α (rHIL-1α or IL-1) protected the intestinal crypt cells of mice against X-ray-induced damage. The survival of crypt cells measured in terms of their ability to form colonies of regenerating duodenal epithelium in situ was increased when IL-1 was given either before or after irradiation. The maximum degree of radioprotection was seen when the drug was given between 13 and 25 h before irradiation. The IL-1 dose producing maximum protection was about 6.3 μg/kg. This is the first report indicating that the cytokine IL-1 has a radioprotective effect in the intestine. The finding suggests that IL-1 may be of potential value in preventing radiation injury to the gut in the clinic.