Background: Atopic disorders have been associated with a Th-2 cytokine predominance. This study investigated Th1- and Th2-related gene expression in asthmatics, atopics and healthy individuals.
Methods: We compared Th1- and Th2-related in vivo-signals using gene expression arrays in 18 atopic asthmatics, 8 atopic non-asthmatic and 14 healthy control subjects. Purified mRNA from peripheral blood mononuclear cells was reverse-transcribed and hybridised to cDNA membranes. Group differences were assessed after standardisation with Mann-Whitney U-test.
Results: Atopic individuals had upregulated lymphotoxin-alpha and downregulated IFNGR1. On the other hand, they had particularly high IL-4, IL-5 and IL4R levels, together with significantly upregulated IL10. Asthmatic individuals had normal Th1-gene expression, but an upregulation og Th-2 genes. Atopic individuals had high, asthmatic individuals excessively high IL12RB1-levels. No Th-2 gene was downregulated in both atopic phenotypes. The expression of IL6R correlated with the daily dose of inhaled corticosteroids.
Conclusions: Atopic individuals had a down regulation of key TH1- and Th2-genes, resulting in a balanced upregulation of Th-specific genes. In contrast, asthmatic subjects had normal Th1-gene expression but a constant upregulation of Th2-specific genes, leading to Th2-predominance.