Influence of anti-allergic agents on in vivo expression of co-stimulatory molecules in normal mice.

The co-stimulatory signal provided by the interaction between CD28 and its ligands, CD80 and CD86, is critical for T cell activation. Engagement of CD40 and CD40L is also essential for IgE synthesis and secretion. In the present study, we examined the influence of anti-allergic drugs on co-stimulatory molecule (CD40, CD80 and CD86) expression in normal mouse splenocytes by flow cytometry. Treatment of BALB/c mice with azelastine (AZ) at a dose of 50.0 micrograms/kg/day, which is the most effective therapeutic dose, for two weeks scarcely affected the expression of co-stimulatory molecules CD40, CD80 and CD86 on splenocytes, whereas a three-week treatment strongly suppressed the expression of these molecules. We also examined the influence of terfenadine (TR) on co-stimulatory molecule expression. The expression of molecules on splenocytes was inhibited when donor mice were treated orally with 2.0 mg/kg/day of TR for three weeks. However, it was not inhibited during a two-week period treatment. These results suggest that the attenuating effects of anti-allergic agents on the diseases may be explained, in part, by their inhibitory action of co-stimulatory molecule expression.