BACKGROUND: Interleukin (IL)-12 is a relatively new and structurally distinct TH1-associated cytokine produced by B cells and macrophages, which may play a suppressive role in the development of allergic sinonasal mucosal responses. OBJECTIVE: We investigated the expression of IL-12 (inducible p40 subunit) and its receptor (IL-12R beta2 subunit) in tissue biopsies of naturally exposed patients with allergy-associated (ACS) and nonallergy-associated chronic sinusitis (NCS) and compared it with controls. We also examined IL-12 and IL-12R expression in biopsies from a ragweed allergen challenge model. In the allergen challenge model, the effect of pretreatment with topical corticosteroids on IL-12 and IL-12R expression was assessed. METHODS: To detect IL-12 and IL-12R mRNA, we employed the technique of in situ hybridization using digoxigenin-labelled riboprobes. RESULTS: In both ACS and NCS subjects there was decreased expression of IL-12 as compared with control (P < 0.05). IL-12R (beta2) expression was decreased in ACS subjects as compared with control (P < 0.05), however, there was no significant difference found between NCS subjects and control. In the allergen challenge subjects, there was a significant decrease in IL-12 expression following challenge (P < 0.05). This effect was abrogated by pretreatment of the subjects with topical corticosteroids. However, IL-12R (beta2) expression showed no change following allergen challenge while pretreatment with topical corticosteroids resulted in increased expression of the (beta2) receptor after allergen challenge (P < 0.05). CONCLUSION: Our data suggest that IL-12 plays a role in the in vivo suppression of the allergic inflammatory response and that the control of this suppression may be exerted largely via the IL-12 (beta2) receptor.
BACKGROUND: Interleukin (IL)-12 is a relatively new and structurally distinct TH1-associated cytokine produced by B cells and macrophages, which may play a suppressive role in the development of allergic sinonasal mucosal responses. OBJECTIVE: We investigated the expression of IL-12 (inducible p40 subunit) and its receptor (IL-12R beta2 subunit) in tissue biopsies of naturally exposed patients with allergy-associated (ACS) and nonallergy-associated chronic sinusitis (NCS) and compared it with controls. We also examined IL-12 and IL-12R expression in biopsies from a ragweed allergen challenge model. In the allergen challenge model, the effect of pretreatment with topical corticosteroids on IL-12 and IL-12R expression was assessed. METHODS: To detect IL-12 and IL-12R mRNA, we employed the technique of in situ hybridization using digoxigenin-labelled riboprobes. RESULTS: In both ACS and NCS subjects there was decreased expression of IL-12 as compared with control (P < 0.05). IL-12R (beta2) expression was decreased in ACS subjects as compared with control (P < 0.05), however, there was no significant difference found between NCS subjects and control. In the allergen challenge subjects, there was a significant decrease in IL-12 expression following challenge (P < 0.05). This effect was abrogated by pretreatment of the subjects with topical corticosteroids. However, IL-12R (beta2) expression showed no change following allergen challenge while pretreatment with topical corticosteroids resulted in increased expression of the (beta2) receptor after allergen challenge (P < 0.05). CONCLUSION: Our data suggest that IL-12 plays a role in the in vivo suppression of the allergic inflammatory response and that the control of this suppression may be exerted largely via the IL-12 (beta2) receptor.