Serum tryptase in allergic rhinitis: effect of cetirizine treatment.

Activated mast cells release a large range of potent mediators of allergic inflammation, including proteases. The tryptase serum levels were evaluated in 13 subjects suffering from allergic perennial rhinitis. Moreover the effects of cetirizine treatment on serum tryptase were studied using the UniCap™ tryptase fluoroenzymeimmunoassay. In allergic patients the serum tryptase values (M±SD: 6.1 ± 2.4 μg/L) were significantly (p < 0.02) higher than the values detected in controls (3.0 ± 1.2 μg/L). In allergic rhinitis, after antihistamine treatment, tryptase values (4.4 ± 1.8 μg/L) decreased significantly (p < 0.001). After two weeks from the cetirizine stop, the tryptase levels increased again (5.5 ± 2.6 μg/l). The results demonstrate that mast cells are constantly activated in perennial allergic rhinitis. The antihistamine treatment is effective in reducing the tryptase release from mast cells, but the mechanism of action of cetirizine is still to understand.