Human interleukin 3: analysis of the gene and its role in the regulation of hematopoiesis.

Interleukin 3 (IL-3) is one of a family of cytokines believed to be important in regulating the growth and development of cells of both the hematopoietic and immune systems. In comparison with other hematopoietic growth factors, IL-3 preferentially supports the proliferation and differentiation of progenitors at early stages of hematopoietic development. In addition, IL-3 exerts a wide spectrum of biological activities on various target cell populations, including T cells, B cells, eosinophils, basophils and monocytes. The direct interaction between IL-3 and early multipotential progenitors has been confirmed in the primate model in which pretreatment of IL-3 primed the animals to become more responsive to late-acting hematopoietic growth factors, like granulocyte-macrophage colony-stimulating factor and erythropoietin. Furthermore, administration of IL-3 can diminish myelosuppression and accelerate hematopoietic recovery in primates treated with various chemotherapeutic drugs. These studies suggest that IL-3 alone or in combination with other hematopoietins may prove to be useful in treating myelosuppressed patients.