Aberrant mast-cell differentiation in mice lacking the stem-cell leukemia gene

Abstract

The stem cell leukemia (SCL) gene encodes a basic helix-loop-helix transcription factor expressed in erythroid, megakaryocyte, and mast-cell lineages. SCL is essential for growth of megakaryocyte and erythroid progenitors. We have used a conditional knockout of SCL (SCL -/Δ) to examine its function in mast cells, critical effectors of the immune system. SCL-/Δ mice had markedly increased numbers of mast-cell progenitors (MCPs) within the peritoneal fluid, bone marrow, and spleen. Fractionation of bone marrow myeloid progenitors demonstrated that these MCPs were present in the megakaryocyte-erythroid- restricted cell fraction. In contrast, unilineage MCPs from control mice were present in the..