Novel role of interleukin 7 in myelopoiesis: stimulation of primitive murine hematopoietic progenitor cells.

Interleukin 7 (IL-7) has been demonstrated to be an important regulator of the growth of B and T cell precursors as well as mature T cells, whereas IL-7 has been reported to have no direct myeloproliferative effects. Here we show that IL-7 potently and directly enhances colony stimulating factor-induced myeloid colony formation from Lin-Sca-1+ murine bone marrow progenitor cells, increasing the cloning frequency up to ninefold and cell numbers up to 50-fold, without affecting their ability to differentiate along the myeloid lineages In contrast, IL-7 has no effect on proliferation of committed Lin- myeloid progenitors. Thus, in addition to its established lymphopoietic potential, this study implicates a novel role of IL-7 in early myelopoiesis.