Expression and regulation of myeloid-specific genes in normal and leukemic myeloid cells.

URING THE process of myeloid differentiation, pluriD potent hematopoietic stem cells become committed to myeloid precursor cells and eventually differentiate into functional, morphologically distinct end-stage myeloid cells. This process is accompanied by the coordinate expression of numerous genes. Molecular biology has made possible cloning, analysis of regulation of expression, and characterization of chromosomal structure of many of these genes. Simplistically, and for ease of experimental design, genes regulated during myeloid differentiation can be catalogued as those tha t code for ubiquitously expressed (“housekeeping”) proteins necessary for normal cellular proliferation and survival, for proteins important for cellular differentiation, cellular recognition and cell/cell interactions, and for gene products important for specific functions of the different end-stage myeloid cells. Cell lines established from human leukemic blasts have frequently served as homogenous and well-defined cell populations that provide both a source of nucleic acids for isolation of complementary DNAs (cDNAs) of myeloid-specific genes, and as models to study the regulation of these genes. In this review, we will focus on work that has been done to isolate and analyze genes specifically expressed in myeloid cells. This includes genes coding for secreted and cytoplasmic proteins important for microbicidal activities of these cells as well as surface molecules involved in cell adhesion and Ig binding. In addition, studies examining the patterns of expression and regulation of cytokines by normal and leukemic myeloid cells will be reviewed.