Effect of Experimental Influenza A Infection on the Nasal Response to Histamine Challenge in Allergic and Non-Allergic Subjects

To determine if a viral upper respiratory tract infection can alter the responsiveness of the nasal mucosa, paired intranasal histamine challenge sessions were performed before and after (8 days) intranasal inoculation with influenza A virus in 16 nonallergic and 16 allergic subjects. The nasal response to a 1-mg histamine challenge was measured as symptom scores for rhinorrhea and congestion, counts for sneezing, weight for expelled secretions, and inspiratory conductance for nasal patency. After inoculation, a total of 25 subjects (11 allergic, 14 nonallergic) became infected with influenza A virus. In infected subjects the measured responses to histamine for secretion weight and rhinorrhea symptom score were significantly greater at 8 days postinfection when compared to those responses recorded prior to inoculation. No significant between session differences were observed for the other responses, or for any of the responses in the uninfected subjects. Significant differences between infected allergic and nonallergic subjects were not observed for any response. These results document an increased secretory response of the nose to histamine during the postsymptomatic period of influenza A viral infection in both allergic and nonallergic subjects.