Identification of cytokine-regulated genes in human leukocytes in vivo.

BACKGROUND Human polymorphic nuclear granulocytes (PMNs) such as neutrophils and eosinophils play a critical role in mediating inflammatory responses to microbial and parasitic infections. Exposure of these leukocytes to cytokines leads to an amplification of granulocyte effector functions by a mechanism termed "priming." Although many studies have investigated the effects of granulocyte priming, little is known concerning the molecular mechanisms that lead to this phenomenon. OBJECTIVE The purpose of this study was to identify potential markers for granulocyte priming and thus also to gain further insight into the pathogenesis of inflammatory responses. METHODS We used a modified differential display technique, random arbitrary primed-PCR to identify genes regulated during the priming of human polymorphic nuclear granulocytes by GM-CSF in vitro. Genes identified were validated by Northern blot analysis of in vitro and in vivo primed leukocytes. RESULTS Several genes were identified and their expression characterized in vitro. One of these genes, 5-lipoxygenase-activating protein, was also found to be up-regulated in leukocytes isolated after allergen challenge of allergic asthmatic patients. CONCLUSION The use of differential display technology is a rapid and effective means of identifying genes whose expression is regulated by priming in vitro and in vivo. Further analysis will lead to a better understanding of the priming phenotype and may provide further insight into the pathologic mechanisms of inflammatory processes.