Summary

Clonogenicity, gene expression and phenotype during neutrophil versus erythroid differentiation of cytokine-stimulated CD34+ human marrow cells in vitro Haematopoietic stem cells develop into progenitor cells committed to one lineage of differentiation through a process governed by transcription factors and stimulated by haema-topoietic growth factors to sustain survival and proliferation (Zhu & Emerson, 2002). Gene targeting experiments in mice and overexpression of certain genes in transduced cell lines of human or murine origin have provided important information about the role of many of the genes critical for haematopoietic development and terminal differentiation. Results from a number of such studies have formed our present under-standing of haematopoietic differentiation. It is generally believed that early neutrophil commitment depends on the transcription factors CCAAT/enhancer-binding protein (C/EPB)-a, PU.1, RAR, core-binding factor (CBF) and c-Myb, and terminal neutrophil differentiation on C/EBP-e and PU.1 (Friedman, 2002). Likewise, GATA-1, FOG-1, erythroid Kruppel-like factor (EKLF) and core-binding protein (CBP) are essential for early erythroid and megakaryocytic development (Cantor & Orkin, 2002). However, only selected parts of the developmental schemes have been confirmed in studies of primary human progenitors and their progeny. For instance, single cell reverse transcription polymerase chai