Relationship between plasma cell levels and profile of bronchoalveolar lavage fluid in patients with subacute extrinsic allergic alveolitis.

BACKGROUND Plasma cells are usually absent in bronchoalveolar lavage (BAL) fluid. Extrinsic allergic alveolitis is associated with increased numbers of T and B lymphocytes in BAL fluid, as well as the presence of a few plasma cells. The aim of this study was to investigate whether there is a relationship between the presence of plasma cells and other cells, and immunoglobulin levels in BAL fluid of patients with extrinsic allergic alveolitis. METHODS Thirty non-smoking patients with extrinsic allergic alveolitis who had a bronchoalveolar lavage 2-7 days after their last exposure to the causative antigen were selected, retrospectively. RESULTS Patients suffering from extrinsic allergic alveolitis with plasma cells in the BAL fluid (n = 18) had increased absolute numbers of lymphocytes, eosinophils and mast cells, a decreased percentage of alveolar macrophages and lower CD4/CD8 ratio, as well as higher immunoglobulin levels, when compared with patients with extrinsic allergic alveolitis having no plasma cells in the BAL fluid (n = 12). CONCLUSIONS The results suggest a relationship between the presence of plasma cells and the other constituents in BAL fluid and a more intense alveolitis. In addition there was a positive relationship between the number of plasma cells in BAL fluid and immunoglobulin levels. These data support the concept of local production of immunoglobulins by plasma cells in the lung following antigen exposure in susceptible individuals.