Invariant natural killer T cells in chronic obstructive pulmonary disease

Background and objective: Invariant natural killer T (iNKT) cells may play an important role in regulating the innate and acquired immune systems in chronic obstructive pulmonary disease (COPD). However, there is little information regarding the potential role of iNKT cells in the pathogenesis of COPD. To investigate whether iNKT cells have an important role in COPD, the frequency of iNKT cells in peripheral blood of patients with COPD was analysed. Methods: This was a comparative study of 28 patients with COPD and 19 age-matched healthy control subjects. Blood iNKT cells were stained with 6B11 mAb, anti-T cell receptor V alpha 24 mAb, anti-T cell receptor V beta 11 mAb or a-galactosylceramide-loaded CD1d-tetramer, and analysed by flow cytometry. Results: The frequency of CD4(+) 6B11(+) iNKT, CD4+ V alpha 24(+) iNKT, CD4(+) V beta 11(+) iNKT and CD3(+) 6B11(+) iNKT cells was significantly lower in peripheral blood of patients with COPD than in that of healthy control subjects. The frequency of CD4(+) 6B11(+) iNKT cells was significantly lower in patients with exacerbations of COPD compared with those with stable COPD. Conclusions: The frequency of iNKT was decreased in peripheral blood of patients with COPD. These results strongly suggest that iNKT cells may play an important role in the pathogenesis of COPD.