Density of phenotypic markers on BAL T-lymphocytes in hypersensitivity pneumonitis, pulmonary sarcoidosis and bronchiolitis obliterans with organizing pneumonia.

In vitro studies have shown that the density of surface antigens reflects the degree of activation of T-cells. We therefore studied the density of surface antigens on T-cells from bronchoalveolar lavage fluid (BALF) and blood in patients with sarcoidosis, hypersensitivity pneumonitis (HP) and bronchiolitis obliterans with organizing pneumonia (BOOP). BALF cells were stained with anti-CD3, anti-CD4, anti-CD8 and anti-human leucocyte antigen-DR(HLA-DR) monoclonal antibodies, and were analysed by cytoflowmetry. The density was evaluated by measuring the Mean Channel fluorescence intensity of the stained cells. The results demonstrated a significant increase in the CD3 density in patients with hypersensitivity pneumonitis (108.2 +/- 20.2 MC), compared with those with pulmonary sarcoidosis (51.2 +/- 12.6), BOOP (74.5 +/- 29.3), and healthy controls (57.1 +/- 11.5). Similar results were obtained for the CD4 and CD8 density in patients with HP. Although the number of HLA-DR positive cells was increased, the density was lower in patients with sarcoidosis (57.4 +/- 11.6) and hypersensitivity pneumonitis (57.4 +/- 14.8), than in healthy controls (72.2 +/- 15.1). Comparable changes were not observed in the peripheral blood. These results suggest that T-cell activation in hypersensitivity pneumonitis may be associated with an increase in the CD3, CD4, and CD8 density on BALF T-cells.