IMMUNOHISTOCHEMICAL ANALYSIS OF NASAL BIOPSIES DURING RHINOVIRUS EXPERIMENTAL COLDS

Human rhinoviruses (HRV) are an important cause of upper respiratory t ract infection and are etiologically linked with asthma exacerbations. However, the mechanisms of virus-induced inflammation are largely unk nown. We examined nasal mucosal biopsies for the presence of an associ ated inflammatory cellular infiltrate during experimental rhinovirus i nfection. A group of 21 adult volunteers (10 atopic) had baseline nasa l biopsies, followed 2 wk later by inoculation with HRV Serotype 16. N asal biopsies were taken on Day 4 of the cold and again 6-10 wk later. Infection was documented by symptom scores, viral culture, and seroco nversion. The biopsies were fixed in acetone and processed into glycol methacrylate resin for semithin sectioning. Mast cells, eosinophils, lymphocytes, and neutrophils were identified with appropriate monoclon al antibodies and a streptavidin-biotin horseradish peroxidase techniq ue. There were no significant changes in the numbers of inflammatory c ells present during the cold or the convalesce nt period compared with baseline biopsies (Wilcoxon paired, p > 0.05). There were also no dif ferences between normal and atopic groups. We suggest that rhinoviral colds are not associated with increased inflammatory cellularity and t hat other mechanisms, such as increased mediator release, are responsi ble for coryzal symptoms.