The role of chemical mediators in eosinophil infiltration in allergic rhinitis in mice.

The involvement of chemical mediators other than histamine in eosinophil infiltration in the nasal mucosa was studied using histamine H(1) receptor-deficient mice. Histamine H(1) receptor-deficient mice and wild-type controls were immunized with ovalbumin and consecutive topical antigen instillation was performed. Histological alterations and eosinophil infiltration into the nasal mucosa of mice were examined. Diffuse infiltration of inflammatory cells and edema after sensitization with antigen were observed in the nasal mucosa in both wild-type and histamine H(1) receptor-deficient mice. The number of eosinophils in the nasal mucosa in mice sensitized with antigen was significantly increased as compared with controls. The number of eosinophils in the nasal mucosa was significantly decreased by cetirizine and epinastine, ramatroban and zafirlukast in wild-type mice. Not only histamine but also thromboxane A(2) and leukotrienes play important roles in allergic rhinitis, especially in the late phase participating in nasal eosinophilia.