Reduction of radioantibody-induced myelotoxicity in hamsters by recombinant interleukin-1

Recombinant human interleukin 1 (IL-1) administered i.p. to tumor-bearing hamsters results in a dose-dependent 2- to 5-fold increase in total peripheral white blood cells. These levels remain elevated for 2 to 3 wk and then decline to base-line levels. Pretreatment of animals with similar doses of IL-1 prevents radioimmunotherapy-induced destruction of the radiosensitive hematopoietic system. Furthermore, recovery from radio-immunotherapy-induced myelosuppression is possible if animals are given IL-1 1 wk after radioimmunotherapy treatment. Thus, both protection and rescue from the hematopoietic damage associated with radioantibody treatment are feasible by pre- or posttreatment with IL-1.