Background: Chronic sinusitis (CS) with asthma generally exhibits a high degree of sinus tissue eosinophilia and recurrence often occurs even after surgical therapy. However, the cause has not yet been fully clarified.
Aims of the study: To elucidate the pathogenesis of this refractory disease, we examined the infiltration of natural killer T (NKT) and type 1 helper T (Th1)/type 2 helper T (Th2) cells, and the cytokine expression in the sinus mucosa.
Methods: Sinus mucosal specimens were obtained surgically from 16 CS patients with nasal polyps. The NKT cells, Th1/Th2 cells and the expression of IL-4, IL-5, IL-13 and IFN-gamma were examined by a polymerase chain reaction or flow cytometry. Nasal mucosal specimens from six other patients with allergic rhinitis (AR) were examined in a similar manner.
Results: The NKT cells were detected to varying degrees in the sinus mucosa from asthmatic CS patients, but neither in the nonasthmatics nor in the nasal mucosa from the patients with AR. The Th2 cells and Th2 cytokines were expressed at significantly higher levels in the sinus mucosa from the CS patients with asthma in comparison to those without asthma. However, the Th1 cell infiltration and IFN-gamma expression were not different between these groups.
Conclusion: Natural killer T cells may, therefore, play important roles in the enhanced Th2 cytokine expression and increased infiltration of Th2 cells and eosinophils observed in the sinus mucosa from asthmatic CS patients through MHC-independent mechanisms.