Longitudinal studies of clinical and immunological parameters in Hypersensitivity pneumonitis.

Twelve subjects with Hypersensitivity Pneumonitis (HP) were followed at 6 months intervals. The parameters studied were: the amount and phenotype of cells recovered from bronchoalveolar lavage (BAL) including the analysis of T cell subsets using monoclonol antibodies, chest x-ray, lung function, serum and BAL precipitins, exposure to the antigen and steroid therapy. At the first examination BAL fluid showed an increase in number of cells compared with controls, a percentage of lymphocytes greater than 80% and a marked reversal in OKT4/OKT8 ratio. Such impairments were observed 6 and 12 months later. Antigen exposure, steroid treatment and the improvement of clinical, physiological and radiological findings didn't influence the BAL features. Our data suggest that an high intensity lymphocitic alveolitis is a long standing process in HP