Interleukin 1-induced sequential myelorestoration: dynamic relation between granulopoiesis and progenitor cell recovery in myelosuppressed mice.

The myelorestorative effect of recombinant human interleukin 1 alpha (IL-1 alpha) was studied in mice treated with anticancer drugs. The treatment of mice with 5-fluorouracil (5-FU; 250 mg/kg body weight) or cyclophosphamide (CPA; 100 mg/kg) considerably decreased bone marrow or splenic colony-forming units in culture (CFU-C) or neutrophils in blood. The daily administration of IL-1 alpha (100 ng/mouse/day) after 5-FU treatment markedly accelerated the recovery of bone marrow CFU-C. This increase was followed by the recovery of splenic CFU-C and neutrophils in blood. In the CPA-treated mice the recovery of bone marrow CFU-C over the normal level was observed regardless of the administration of IL-1 alpha 3 days after CPA treatment. The daily administration of IL-1 alpha after CPA treatment markedly increased splenic CFU-C or neutrophils over the normal level following the increase of bone marrow CFU-C. Thus, in both 5-FU- and CPA-treated mice, the increase of bone marrow CFU-C after the administration of IL-1 alpha was observed several days earlier than the increase of splenic CFU-C and neutrophils in blood. The increase of splenic CFU-C and neutrophils in blood was observed concomitantly. The experiments, in which effective timing of IL-1 alpha injection was examined, indicated that the administration of IL-1 alpha within a few days after treatment with anticancer drugs was necessary for the accelerated recovery of bone marrow progenitor cells. On the other hand, the effective recovery of splenic progenitor cells and peripheral neutrophils required the administration of IL-1 alpha after the increase of bone marrow progenitor cells. Thus, the administration of IL-1 alpha daily or every other day was the most effective for recovery from myelosuppression induced by anticancer drugs.