Therapeutic evaluation of interleukin-1 for stimulation of hematopoiesis in primates after autologous bone marrow transplantation

A multiple dose IL-1 therapy was evaluated for its capability to stimulate hematopoiesis in normal primates and to restore hematopoiesis after autologous bone marrow transplantation. The administration of IL-1 to normal animals over a dose range of 0.5 to 10 ug/kg/d led to a 7-12 fold increase in peripheral blood neutrophil and monocyte counts after 24 hours. This increase in the mature peripheral blood myeloid cells was followed by changes in the myeloid composition of the bone marrow, where the percentage of myeloid elements increased along with a transient increase in myeloid progenitor cell activity. IL-1 treatment also led to an initial decrease in platelet counts of 10-30% during the first 3 days of treatment. However, a striking finding was a significant and long lasting stimulation of increased platelet production with platelet counts increasing to 77% of baseline 3 days after cessation of treatment and remaining elevated for the next 10 days. The therapeutic potential of the IL-1 regimen to restore hematopoiesis was further evaluated in an established autologous bone marrow transplantation model. In monkeys receiving IL-1 doses, 1.0 and 5.0 ug/kg/d, neutrophil counts recovered to >0.5 x 10e9/1 on day 16, one day earlier than control, but the recovery to baseline neutrophil counts occurred 5 days sooner than control. IL-1 therapy had its greatest effect on the restoration of platelet counts after transplantation, reaching >100 x 10e9/l by day 21, two weeks earlier than control. This work demonstrates that IL-1 therapy stimulates myelopoiesis but its most promising clinical application is the stimulation of platelet production.