Study objectives: The dysregulation of apoptosis and the expression of apoptosis-related molecules of allergen-reactive T lymphocytes have been suggested to play a key role in the development and maintenance of the inflammatory reactions in allergic asthma. Glucocorticoids are effective drugs for treating allergic inflammation. In this study, we investigated the effect of dexamethasone (DEX) on the apoptosis and B-cell lymphoma (Bcl)-2 expression of peripheral blood T lymphocytes as well as the soluble form of Fas (sFas) in allergic asthmatic patients.
Methods: Peripheral blood lymphocytes from 41 allergic asthmatic patients and 30 age-matched and sex-matched control subjects were treated with 0.1 and 1 μM DEX. The percentages of apoptosis and expression of the Bcl-2 molecule in T lymphocytes were assessed by flow cytometry. The plasma concentration of sFas was measured using the enzyme-linked immunosorbent assay.
Results: DEX (0.1 and 1 μM) could induce the apoptosis of T lymphocytes from allergic asthmatic patients and control subjects in a dose-dependent manner in vitro. The apoptotic susceptibility of T lymphocytes to DEX and the plasma sFas concentration were significantly higher in allergic asthmatics. The ex vivo expression of Bcl-2 was significantly lower in the T lymphocytes of asthmatic patients than in those of the control subjects. However, DEX did not have any significant effect on the expression of Bcl-2 in vitro.
Conclusions: The T lymphocytes of asthmatic patients have higher apoptotic susceptibility to DEX treatment in vitro and a lower expression of the Bcl-2 molecule.