A 7-YEAR FOLLOW-UP-STUDY OF LUNG-FUNCTION AND METHACHOLINE RESPONSIVENESS IN SENSITIZED AND NONSENSITIZED WORKERS HANDLING LABORATORY-ANIMALS

Lung function, studied with spirometry, nitrogen washout technique, an d methacholine responsiveness, was prospectively investigated in a sev en-year follow-up study of 35 laboratory animal workers (19 women and 16 men) of whom 11 were skin prick test (SET) positive to laboratory a nimal allergens; five had asthma and six had rhinitis symptoms. During the follow-up, 82 % of the SPT-positive subjects had stopped animal w ork, compared with 29 % of the SPT-negative subjects, In baseline spir ometry, there wets no decrement in the lung volumes or differences bet ween SPT-positive and SPT-negative subjects, At followup, no differenc e was found in vital capacity (VC), forced expiratory volume during on e second (FEV1), or residual volume (RV), but the volume of trapped ga s (VTG), which is assumed to measure small airways, had increased with a median of 11 mL (P = 0.03). Subjects sensitized to laboratory anima ls had a minor increase in methacholine responsiveness in FEV1 at foll ow-up (P = 0.03). The VTG responsiveness was already increased in the first examination (P = 0.035) and remained so at follow-up. Furthermor e, the FEV1 responsiveness could predict a subsequent decline in basel ine VC and FEV1. In conclusion, our results support the hypothesis tha t airway responsiveness in immunoglobulin E-mediated allergy might sta rt in small airways and subsequently affect large airways.