Increased expression of HLA-DR antigen on alveolar macrophages in pulmonary diseases

The expression of HLA-DR antigen on alveolar macrophages obtained by bronchoalveolar lavage in healthy controls and patients with different diseases was investigated, using cytofluorographic analysis and phykoerythrin conjugated monoclonal mouse anti-human HLA-DR antibody. Alveolar macrophages in patients with extrinsic allergic alveolitis (n = 4), idiopathic lung fibrosis (n = 4), sarcoidosis (n = 6), rheumatoid lung disease (n = 6) and pulmonary infection (n = 5) showed increased density of HLA-DR antigen expression compared to healthy control subjects (n = 5). The increased expression of HLA-DR antigen on alveolar macrophages confirms the importance of these cells for recognition of antigens and immunological responses in different pulmonary diseases.