Coronavirus-induced common cold and allergen-induced rhinitis are characterized by nasal mucosal exudation of bulk blood plasma. The mucosal exudation process involves 'flooding' of the lamina propria with plasma-derived binding proteins and it is possible that subepithelial inflammatory cytokines and mediators may be moved by the exudate to the mucosal surface. In this study, we have analysed cytokine levels in nasal lavage (NAL) fluids from non-allergic subjects inoculated with coronavirus (n = 20) and from subjects with allergic (birch pollen) rhinitis subjected to additional allergen challenge (samples were obtained 35 min post challenge) in the laboratory (n = 10). Ten of the 20 inoculated subjects developed common cold and 10 remained healthy. Interferon-gamma (IFN gamma), interleukin-1 beta (IL-1 beta), granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-4, and IL-6 were analysed in unprocessed NAL fluids using immunoassays. The subjects who developed common cold had increased NAL fluid levels of IFN gamma (P < 0.05) that correlated well with the symptoms (P < 0.001). IFN gamma did not increase in subjects with allergic rhinitis. IL-1 beta levels were similar in NAL fluids obtained from all inoculated subjects. In the subjects with allergic rhinitis NAL fluid levels of both IL-1 beta and GM-CSF were increased (P < 0.05). GM-CSF was not detected in common cold. IL-4 and IL-6 were not detectable in any of the NAL fluids. The present cytokines may not only emanate from superficial mucosal cells. By aiding plasma exudation subepithelial cytokines may potentially also be retrieved on the mucosal surface.(ABSTRACT TRUNCATED AT 250 WORDS)