Local expression of ϵ germline gene transcripts and RNA for the ϵ heavy chain of IgE in the bronchial mucosa in atopic and nonatopic asthma

Background: The demonstration of ϵ germline gene (Cϵ) transcripts and mature mRNA for the ϵ heavy chain gene (Iϵ) in the nasal mucosa suggested that IgE synthesis may occur in allergic rhinitis. Objective: In view of our previous demonstration of increases in IL-4 mRNA + cells in asthmatic subjects, we assessed whether local IgE synthesis may also be a feature of bronchial asthma. Methods: Fiberoptic bronchoscopic mucosa biopsy specimens were obtained from 9 atopic asthmatic subjects and 10 nonatopic normal (intrinsic) control subjects. To control for atopy, we also studied 9 nonatopic asthmatic subjects and 10 atopic nonasthmatic control subjects. Tissue was processed for immunohistochemistry for B cells (CD20) and in situ hybridization for Iϵ and Cϵ RNA + cells and IL-4 mRNA + cells. Results: B-cell numbers in the bronchial mucosa were similar for asthmatic subjects compared with control subjects, whereas significantly higher numbers of Iϵ RNA + ( P = .02 and P = .04, respectively), Cϵ RNA + ( P = .01 and P = .03, respectively), and IL-4 mRNA + ( P = .001 and P = .001, respectively) cells were observed in atopic asthmatic subjects and nonatopic asthmatic subjects, respectively, but not in atopic control subjects compared with nonatopic control subjects. In asthmatic subjects there were significant correlations between Iϵ RNA + cells ( r = 0.54, P = .02) and Cϵ RNA + cells ( r = 0.48, P = .05) when compared with the number of IL-4 mRNA + cells. Conclusion: Increases in Iϵ and Cϵ RNA + cells, but not B-cell numbers, in the bronchial mucosa provide evidence for local IgE synthesis in both atopic and nonatopic asthma. These changes appear to relate to asthma rather than atopy per se and, at least in part, may be under the regulation of IL-4. (J Allergy Clin Immunol 2001;107:686-92.)