BACKGROUND: In view of recent observations demonstrating that rhinovirus infections are associated with increased local activity of eosinophils, we hypothesized that eotaxin, a selective eosinophil chemoattractant, may be involved in eosinophil recruitment/activation in common cold infections. METHODS: Twenty-three patients with seasonal allergic rhinitis were inoculated with human rhinovirus 16 (HRV 16) outside the pollen season. Sequential diluent and allergen (10(3) SQ-U) challenges, each followed by nasal lavage, were carried out about 3 months before and 4 days after virus inoculation. RESULTS: Seventeen patients developed common cold and were further analyzed. Lavage fluid levels of eotaxin were increased at the height of active common cold (day 4 after inoculation) both at baseline (after diluent challenge) (P<0.01) and acutely after allergen challenge (P<0.05). CONCLUSIONS: Common cold symptoms after nasal HRV 16 inoculation are associated with increased nasal mucosal output of eotaxin, suggesting that this chemokine is partly responsible for recruitment/activation of airway mucosal eosinophils in common cold infections.