EXPRESSION OF EPSILON-GERM-LINE GENE TRANSCRIPTS AND MESSENGER-RNA FOR THE EPSILON-HEAVY-CHAIN OF IGE IN NASAL B-CELLS AND THE EFFECTS OF TOPICAL CORTICOSTEROID

We have studied the expression of the gene encoding the epsilon heavy chain of IgE in nasal B cells of hayfever patients. We developed probe s to detect transcripts of the epsilon germ-line gene and the rearrang ed gene by in situ hybridization of biopsy sections from thee nasal mu cosa. We compared tissue from hayfever patients out of season with tha t of normal controls, and also of hayfever patients treated with topic al corticosteroid (fluticasone propionate) or placebo for 6 weeks and then challenged with antigen. a chain mRNA was expressed in an unexpec tedly high proportion of nasal B cells of both hayfever patients and n ormal subjects. However, although similar numbers of B cells were foun d in both groups, the proportion of cells that express epsilon chain m RNA was several times higher in the hayfever patients. No transcripts of the epsilon germ-line gene were detected in either group before all ergen challenge. When hayfever patients were administered antigen loca lly early (10-30 min) and late (1-24 h) symptoms ensued. After 24 h, c oincident with an increase in the number of cells expressing mRNA for IL-4 in the tissue, a germ-line gene transcripts appeared in the nasal B cells. The induction by allergen of IL-4 mRNA and epsilon germ-line gene transcripts was suppressed by fluticasone propionate treatment. Our results suggest that local IgE synthesis and cytokine regulation o f heavy chain switching to IgE occur in the nasal mucosa.