In an attempt to identify inflammatory mediators that may contribute to rhinorrhea, nasal congestion and other cold symptoms, we recruited 40 healthy young adults (median age, 20) for provocative rhinovirus challenge. Mediators measured included histamine, kinins and enzymes with arginine esterase activity. Volunteers were inoculated with rhinovirus or a sham inoculum. Nasal secretions for viral culture were obtained daily, and volunteers were deemed infected if they shed virus or had a 4-fold or greater increase in serum antibody titer. The virus-infected group was subdivided using the Jackson criteria into an ill or non-ill group; each group was compared to the control group. Of the 27 virus-inoculated subjects, 25 had positive cultures for the challenge virus, and 15 became ill. None of the controls had a positive culture. All variables measured--except histamine--grew stronger in direct relationship with the symptoms as the cold increased in severity. In the infected-ill group, the mean kinin level increased more than 10-fold over baseline. The kinin level remained relatively unchanged in the control and non-ill groups. Similar results were found for levels of albumin and enzymes with arginine esterase activity. Histamine levels remained constant in both the infected-ill and non-ill groups, which suggests that mast cells and basophils do not participate in the pathophysiology of rhinovirus infections and that antihistamines should be ineffective in treating rhinovirus colds. Since volunteers who developed cold symptoms exhibited a notable increase in kinin, a potent inflammatory mediator, we recommend further study of a kinin antagonist in reducing nasal symptoms.