NASAL RESPONSE IN SUBJECTS UNDERGOING CHALLENGES BY INHALING OCCUPATIONAL AGENTS CAUSING ASTHMA THROUGH THE NOSE AND MOUTH

Background Subjects with occupational asthma (OA) often report nasal s ymptoms, but nasal reactions to inhalation challenges with occupationa l agents have not been well characterized. Methods Fifteen subjects wi th OA (eight due to high-molecular-weight agents - flour and guar gum - and seven due to isocyanates) underwent inhalational challenges usin g closed-circuit devices (dry particles for high molecular-weight agen ts and gas generator for isocyanates) on two occasions, 2-4 weeks apar t in a random fashion. On one occasion, they inhaled through the nose and, on another, through the mouth. The FEV1 was monitored for up to 8 h afterward, and symptoms were documented with a standardized questio nnaire on nasal symptomatology, assessment of nasal resistance by rhin omanometry, and nasal lavage for the examination of cells and mediator s. Results inhaling through the mouth and through the nose: 1) yielded similar asthmatic responses (25+/-8% and 22+/-10% maximum changes in FEV1) 2) more than doubled the peak nasal symptoms and nasal resistanc e when the maximum daily response was compared with prechallenge resul ts. This increase occurred on the days of inhalational challenges thro ugh the mouth and through the nose. There were some significant respon ses assessed by nasal lavage in terms of cells and mediators, again wi th no differences between the days of challenges through the mouth and through the nose. Conclusions Inhaling occupational agents of high or low molecular weight, including isocyanates, whether through the mout h or nose: 1) results in a similar asthmatic response 2) causes a sign ificant nasal response in terms of symptoms and an increase in nasal r esistance 3) causes some significant changes in inflammatory cells and mediators.