Kinetics of gene induction after FcεRI ligation of atopic monocytes identified by suppression subtractive hybridization

The high-affinity receptor for IgE, FcεRI, on APCs plays an important role in the initiation and chronicity of inflammatory atopic diseases. To understand the molecular regulation of FcεRI-mediated processes, differentially expressed genes are of great interest to be identified. Suppression subtractive cDNA hybridization has been used to identify genes induced after FcεRI stimulation on atopic monocytes. Overexpression of the identified genes was determined by semiquantitative RT-PCR analysis of transcripts from the tester (stimulated) and driver (unstimulated) monocytes. Results were confirmed and kinetics of the transcripts established using blood cells from additional atopics at 4 and 24 h of FcεRI induction. The following sequences were identified: monocyte chemoattractant protein 1, macrophage-inflammatory protein 1β, IL-6, β_A subunit of inhibin/activin, IFN-stimulated gene of 54 kDa, IL-1R antagonist, and kynurenine 3-monooxygenase. Chemokines are highly expressed during the early and late phase after FcεRI cross-linking, whereas proinflammatory and differentiation stimuli rapidly decline after an initial overexpression. Kynurenine 3-monooxygenase, an enzyme involved in the degradation of the amino acid tryptophan, is significantly up-regulated during the late phase after 24 h of FcεRI induction. These results demonstrate that the analysis of the profile of gene induction following activation of FcεRI on atopic monocytes may reveal how these cells might participate in the regulation of atopic disorders.