This is the first report showing that antihistamines, especially CT, LCT, DL, and FEX, could suppress the OPN production and OPN-induced chemotactic factor, GM-CSF, RANTES, and Eotaxin, production from nasal epithelial cells at similar or lower than therapeutic blood levels, which may be responsible for the attenuating effect of these agents on allergic diseases such as asthma and allergic rhinitis. This evidence concerns the gene CSF2 and allergic rhinitis.