Identification of cytokine-regulated genes in human leukocytes in vivo

Background: Human polymorphic nuclear granulocytes (PMNs) such as neutrophi ls and eosinophils play a critical role in mediating inflammatory responses to microbial and parasitic infections. Exposure of these leukocytes to cyt okines leads to an amplification of granulocyte effector functions by a mec hanism termed "priming." Although many studies have investigated the effect s of granulocyte priming, Little is known concerning the molecular mechanis ms 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 pathogen esis of inflammatory responses. Methods: We used a modified differential display technique, random arbitrar y primed-PCR to identify genes regulated during the priming of human polymo rphic nuclear granulocytes by GM-CSF in vitro. Genes identified were valida ted by Northern blot analysis of in vitro and in vivo primed leukocytes. Results: Several genes were identified and their expression characterized i n vitro. One of these genes, 5-lipoxygenase-activating protein, was also fo und to be up-regulated in leukocytes isolated after allergen challenge of a llergic asthmatic patients. Conclusion: The use of differential display technology is a rapid and effec tive 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.