In vivo effects of recombinant human and murine interleukin-1 alpha (IL-1 alpha) on murine hematopoiesis.

Interleukin-1 alpha (IL-1 alpha) has profound effects on hematopoiesis that could be exploited therapeutically. The cytokine potentiates immature myeloid and erythroid progenitor cells and suppresses late-stage erythropoiesis. To evaluate the species specificity of IL-1 alpha's activities, we compared the dose-related in vivo effects of recombinant murine IL-1 alpha (MuIL-1 alpha) with recombinant human IL-1 alpha (HuIL-1 alpha) on mouse hematopoietic precursor cells. Normal mice were treated with a single i.p. injection of either HuIL-1 alpha or MuIL-alpha at various doses and assayed 48 hours later. MuIL-1 alpha induced a significantly greater suppression of mature erythroid progenitors (CFU-E) than an equivalent dose of HuIL-1 alpha. Likewise, the immature erythroid (BFU-E) as well as the mature macrophage (CFU-M) progenitors were stimulated to a significantly greater extent with MuIL-1 alpha than with HuIL-1 alpha. These results demonstrate that isologous system should be utilized to optimally evaluate the in vivo use of IL-1 alpha for potentiating hematopoiesis.