RHINOVIRUS INFECTION PREFERENTIALLY INCREASES LOWER AIRWAY RESPONSIVENESS IN ALLERGIC SUBJECTS

Rhinovirus (RV) infections are important triggers of acute asthma symp toms in susceptible persons. To determine whether the presence of alle rgy is a risk factor for enhanced lower airway effects during RV infec tion, we experimentally infected (RV16) 18 volunteers with allergic rh initis and 13 normal control subjects and measured the effects on the response of the lower airways to histamine. All subjects were successf ully infected, as indicated by increased upper respiratory symptoms an d RV16 cultured from nasal secretions. The change in histamine PD20(De lta PD20) caused by RV infection was significantly different in allerg ic subjects from that in nonallergic control subjects (Delta PD20 = -0 .40 versus -0.03 log units, p = 0.04). This relationship was strengthe ned after adjusting for initial PD20 and FEV1 (mean Delta PD20 = -0.43 versus 0.01 log units, p < 0.01). The virus-induced Delta PD20 was al so influenced by baseline lung function: there was a positive correlat ion between initial FEV1 and Delta PD20, and a weak but significant ne gative correlation between baseline PD20 and Delta PD20. These finding s indicate that host factors such as allergy, baseline FEV1, and basel ine PD20 influence the changes in lower airway physiology caused by RV infection and raise the possibility that these factors contribute to the increased lower airway effects of RV infection in subjects with as thma.