Identification of genes effected by GM-CSF treatment in mature human neutrophils

The objective of this study was to compare the transcriptional repertoire of mature human neutrophils before and after GM-CSF treatment by using oligonucleotide microarrays. Leukotriene B4 (LTB4) is an important pro-inflammatory lipid mediator generated by neutrophils upon activation. Granulocyte/macrophage colony-stimulating factor (GM-CSF) stimulation is known to enhance agonist-mediated LTB4 production of neutrophils within minutes, a process called “priming”. Here, we demonstrate that GM-CSF also limits the production of LTB4 by neutrophils via a transcriptional mechanism at later time points. We identified hematopoietic specific Ras homologous (RhoH)/translocation three four (TTF), which was induced following GM-CSF stimulation in neutrophils, as a key regulator in this process. Neutrophils derived from RhoH/TTF-deficient (Rhoh-/-) mice demonstrated increased LTB4 production upon activation compared with normal mouse neutrophils. Moreover, neutrophils from cystic fibrosis patients expressed enhanced levels of RhoH/TTF and generated less LTB4 upon activation compared with normal human neutrophils. Taken together, these data suggest that RhoH/TTF represents an inducible feedback inhibitor in neutrophils that is involved in the limitation of innate immune responses. 3 healthy donors' blood were used for each group. Two groups were created. One group ("untreated"=N ) the RNA were extracted immediately after isolation of blood neutrophil. The second group ("Neu") blood neutrophils were incubated with GM-CSF (50 ng/ml) for 7 hours before RNA extraction.