We studied whether epithelial cells cultured in serum-free medium contained other cells or not, there were differences in SCF production from cultured nasal epithelial cells between groups of nonallergic and allergic patients, and among degrees of serum mite-CAP RAST classes of allergic patients, and how drugs inhibited SCF production. As a result, no other contaminating cells except mast cell existed in cultured cells. There was a significant difference in SCF production of cultured cells between nonallergic and class 1-2, 3-4, 5-6, and between class 1-2 and 3-4, 5-6 of mite CAP-RAST class. Cyclosporin, prednisolone, fluticasone, ketotifen, and clemastine inhibited SCF production from cultured epithelial cells, but cromoglicate and suplatast did not. Inhibition means the reduction of SCF from cells, not the growth of cultured nasal epithelial cells.