Interactive effects of steroids and beta-agonists on accumulation of type 2 T cells.

BACKGROUND

Airway inflammation associated with asthma has been reported to be either unaffected or slightly increased by inhaled beta-agonist monotherapy, and concerns regarding disease exacerbations with continuous long-acting beta-agonist monotherapy have prompted the recommendation of concomitant steroid treatment.

OBJECTIVES

Using peripheral blood lymphocytes from asthmatic subjects, we aimed to determine (1) whether short- or long-acting beta-agonists increase IL-13-producing (IL-13+ or IFN-gamma-producing (IFN-gamma+ T-cell numbers and (2) the ability of the corticosteroid budesonide to reverse these effects.

METHODS

Peripheral blood lymphocytes from asthmatic subjects were cultured 6 days ex vivo with IL-2 and various concentrations of albuterol, formoterol, and budesonide. Numbers of IL-13+ and IFN-gamma+ T cells were determined by means of flow cytometric analysis.

RESULTS

Both albuterol and formoterol increased IL-2-stimulated accumulation of IL-13+ T cells, and this increase was highest at concentrations approximating the dissociation constant of each beta-agonist for the beta(2)-adrenergic receptor. Budesonide at greater than 1 nmol/L reversed the augmenting effects of beta-agonists on IL-13+ T-cell accumulation, and budesonide at greater than 10 nmol/L inhibited increases in IL-13+ T cells stimulated by IL-2. Budesonide decreased, whereas beta-agonist did not affect, numbers of total and IFN-gamma+ T cells in IL-2-stimulated cultures.

CONCLUSION

beta-Agonists at physiologically and clinically relevant concentrations stimulate increased antigen-independent, cytokine-stimulated accumulation, specifically of type 2 T cells from asthmatic subjects. The corticosteroid budesonide potently reverses this effect.