High-Density Oligonucleotide Array Analysis of mRNA Transcripts in Peripheral Blood Cells of Severe Atopic Dermatitis Patients

Abstract

Background: There are few laboratory tests for evaluating atopic dermatitis (AD) with the exception of IgE levels or the eosinophil count. We attempted to identify new diagnostic markers by screening the genome-wide expression of transcripts in peripheral blood mononuclear cells (PBMC). Methods: For this study, we enrolled 7 nonatopic healthy volunteers, 5 AD patients who responded well to treatment and 6 who responded poorly. We compared genome-wide transcript levels in PBMC derived from patients with severe AD and healthy volunteers using high-density oligonucleotide arrays (GeneChip, Affymetrix). After the first screening with GeneChip, we employed real-time quantitative PCR to confirm differential expression levels. Results: Screening with GeneChip showed that the levels of a total of 92 transcripts increased at least 3-fold in one population compared to another. After further evaluation of these genes with real-time quantitative PCR, the levels of 4 transcripts were confirmed to be significantly different in PBMC from AD patients compared to controls, namely IFN-γ, TRAIL (TNF-related apoptosis-inducing ligand), ISGF-3 (STAT1) and defensin-1. With the exception of IFN-γ, none of these genes has previously been implicated in AD pathology. Conclusion: These 4 transcripts in PBMC are expected to be useful markers for evaluating AD.