Abstract

This study was designed to determine whether cell populations in bronchoalveolar lavage fluid represent a reflection of disease activity in sarcoidosis. Bronchoalveolar lavage fluid cells were obtained from 22 patients with sarcoidosis and from 10 normal control subjects and investigated by immunocytological methods. A panel of monoclonal antibodies was used to determine the relative proportions of phenotypically distinct subsets of macrophages and lymphocytes in the patients with sarcoidosis and to correlate them with clinical indices, such as disease duration, serum angiotensin converting enzyme, the chest radiograph, and results of pulmonary function tests. Patients with sarcoidosis had a higher percentage than the normal subjects of macrophage like cells expressing RFD1 (a class II associated antigen preferentially expressed by dendritic cells), an epithelioid cell antigen (RFD9), and a circulating monocyte antigen (UCHMI). The increase in RFD1+ cells appeared to be due to detection of antigen by this antibody on cells that were also expressing phenotypic markers of classical tissue macrophages (RFD7). The lymphocytes in lavage fluid from patients with sarcoidosis were characterised by increased expression of activation markers, such as interleukin-2 receptors (anti-Tac+), HLA-DR (RFDR+), and "blast" forms (expressing above normal concentrations of CD7 antigen). This was associated with increased proportions of the CD4+ (helper-inducer) T cell subset. Patients with sarcoidosis whose clinical indices suggested activity showed an increased number of macrophages coexpressing RFD1 and RFD7 antigens, of macrophages expressing UCHM1 and lymphocytes expressing activation markers. The expression of these markers was also increased on lavage cells from patients with radiographic evidence of widespread disease (chest radiographic stage II and III), but there was no relation with disease duration, pulmonary function, or serum angiotensin converting enzyme activity. Immunocytological analysis of lavage cells offers a probe for studying the pathogenesis of sarcoidosis and may be of value in monitoring disease activity.