Extrinsic allergic alveolitis: comparative study of the bronchoalveolar lavage profiles and radiological presentation.

Introduction: Extrinsic allergic alveolitis (EAA) is an immunologically mediated interstitial lung disease. The abnormalities in the bronchoalveolar lavage (BAL) fluid cell counts are almost always seen in patients with EAA according to the stage of the disease. The aim of this retrospective study was to find out how the BAL lymphocyte count, percentage of lymphocytes expressing HLA-DR, CD4/CD8 T cell ratio in BAL fluid, and the concentration of immunoglobulin G in serum correspond to the inflammatory activity of the disease.

Methods: The study included 14 patients with EAA. BAL fluid samples were obtained and processed for cytological and cytometric analysis. Immunoglobulin G serum concentrations were measured. High resolution computed tomography (HRCT) scoring system modified by Gay was used for establishing the alveolar and interstitial score in each patient.

Conclusions: It was found that subjects with normal value of CD4/CD8 ratio in BAL fluid had higher interstitial HRCT score. Clinical presentation, continuous exposure to the causative antigens, and BAL lymphocyte count positively correlated with the alveolar HRCT score. It is proposed that the increased BAL lymphocyte count could be the predictor of the inflammatory activity of the disease, especially in people with lasting exposure to the offending antigen.