NASAL MESSENGER-RNA EXPRESSION OF INTERLEUKIN-2, INTERLEUKIN-4, AND INTERLEUKIN-5 IN PATIENTS WITH ALLERGIC RHINITIS

In nasal biopsies from 17 adult patients with seasonal allergic rhinit is and from 10 healthy controls, cytokines were analyzed by reverse-tr anscriptase polymerase chain reaction (RT-PCR), The time-course study during winter included repeated local allergen provocation with subseq uent nasal biopsies as well as biopsies taken during pollen season. Th e RT-PCR for CD44 yielded positive bands in 65 of 71 cases, in which c ases mRNA for interleukins 2, 4, and 5 (IL-2, IL-4, and IL-5) were thu s investigated by means of seminested PCR. IL-4 mRNA was found almost exclusively in the allergic patients. During provocation a significant increase in IL-4 was noticed compared with controls (p = 0.043). Equa lly, during the natural pollen season, IL-4 mRNA expression was signif icantly higher in patients not using nasal corticosteroids compared wi th those who did (p = 0.011). No differences in IL-2 or IL-5 were obse rved between the groups. These findings also indicate, together with e arlier observations of T-cell activation, a phenotype switch toward T- helper 2 (Th2) cells, and the accumulation (homing) of these T cells i n the nasal mucosa, that T cells constitute the main source for IL-4 i n the nasal mucosa. Therefore, allergic patients have an increased syn thesis of IL-4 when provoked with the allergen, and during natural pol len season this synthesis can be downregulated by corticosteroids. Fur thermore, this study exemplifies the versatility of molecular biology in surgical pathology and that even low-copy-number cytokine mRNA can be examined in routinely snap-frozen surgical specimens.