Inhaled Fluticasone Propionate Downregulates Peripheral Blood T Lymphocyte Activation and Naturel Killer Cells in Asthma

Background:

Inhaled corticosteroids (ICS) are widely used in the treatment of asthma although the exact mechanism of their action is not known. We investigated the effect of a 16-week therapy with inhaled fluticasone propionate (FP; 500 g/day as a dry powdered inhaler) on clinical indices as expressed by FEVb diurnal variation in peak expiratory flow rate (PEFRvar), bronchial hyperreactivity as expressed by histamine challenge test and T lymphocytes, naturel killer (NK) cells and T lym­phocyte activation in peripheral blood in a group of sympto­matic individuals with asthma.

Methods:

Twelve symptomatic asthmatics (mean age was 32.8±1.9) were recruited in the study. Patients were given 500g/d FP for 16 weeks after a two-week run-in period. The results of peripheral blood T lymphocytes and NK cells of six nonasthmatic-nonatopic control subjects were compared with the asthmatics.

Results:

A 16-week treatment with FP had a marked effect of improving clinical parameters including FEVi (p=0.02), PEFRvar (p=0.002) and PC20 (p=0.004). Peripheral blood T lymphocyte activation marker CD25 which was higher than the controls at the beginning, was significantly reduced (p=0.02). The number of CD16/CD56 lymphocytes (Naturel killer=NK cells) were also reduced (p=0.002), although they were not significantly differ­ent from the controls.

Conclusion:

This data suggested that T lymphocyte activa­tion and the number of NK cells in peripheral blood of symptomatic asthmatics can be reduced by a 16-week in­haled fluticasone propionate treatment with the improvement in clinical indices as measured by FEVj, PEER and PC2o values.