DENSITY OF PHENOTYPIC MARKERS ON BAL T-LYMPHOCYTES IN HYPERSENSITIVITY PNEUMONITIS, PULMONARY SARCOIDOSIS AND BRONCHIOLITIS OBLITERANS WITHORGANIZING PNEUMONIA

In vitro studies have shown that the density of surface antigens refle cts the degree of activation of T-cells. We therefore studied the dens ity of surface antigens on T-cells from bronchoalveolar lavage fluid ( BALF) and blood in patients with sarcoidosis, hypersensitivity pneumon itis (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 ana lysed by cytoflowmetry. The density was evaluated by measuring the Mea n Channel fluorescence intensity of the stained cells. The results dem onstrated a significant increase in the CD3 density in patients with h ypersensitivity pneumonitis (108.2+/-20.2 MC), compared with those wit h 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 positi ve cells was increased, the density was lower in patients with sarcoid osis (57.4+/-11.6) and hypersensitivity pneumonitis (57.4+/-14.8), tha n in healthy controls (72.2+/-15.1). Comparable changes were not obser ved in the peripheral blood. These results suggest that T-cell activat ion in hypersensitivity pneumonitis may be associated with an increase in the CD3, CD4, and CD8 density on BALF T-cells.