Submitted October 1, 2008
Accepted March 25, 2009
Changes in gene expression of granulocytes during in vivo G-CSF/dexamethasone mobilization for transfusion purposes
Agata Drewniak*, Bram J. van Raam, Judy Geissler, Anton T.J. Tool, Olaf R.F. Mook, Timo K. van den Berg, Frank Baas, and Taco W. Kuijpers
Sanquin Research and Landsteiner Laboratory, Department of Blood Cell Research, Amsterdam, Netherlands
Emma Children's Hospital, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands
Department of Neurogenetics, Academic Medical Center, Amsterdam, Netherlands
* Corresponding author; email: a.drewniak{at}sanquin.nl.
Treatment of healthy donors with G-CSF and dexamethasone results in sufficient numbers of circulating granulocytes to prepare granulocyte concentrates for clinical purposes. Granulocytes obtained in this way demonstrate relatively normal functional behavior combined with a prolonged life span. To study the influence of mobilizing agents on granulocytes, we used oligonucleotide microarrays to identify genes that are differentially expressed in mobilized granulocytes as compared to control granulocytes. More than 1000 genes displayed a differential expression pattern, with at least a three-fold difference. Among these, a large number of genes was induced that encode proteins involved in inflammation and the immune response, such as C-type lectins and leukocyte immunoglobulin-like receptors. Since mobilized granulocytes have a prolonged life span, we focused on genes involved in the regulation of apoptosis. One of the most prominent among these was CAST, the gene encoding calpastatin. Calpastatins are the endogenous inhibitors of calpains, a family of calcium-dependent cysteine proteases recently shown to be involved in neutrophil apoptosis. Transcriptional activity of the CAST gene was induced by G-CSF/dexamethasone treatment, both in vivo and in vitro, while the protein expression of CAST was stabilized during culture. These studies provide new insight in the genotypic changes as well as in the regulation of the immunological functions and viability of mobilized granulocytes used for clinical transfusion purposes.
