INCREASED NUMBER OF ALVEOLAR MACROPHAGES EXPRESSING SURFACE MOLECULESOF THE CD11 CD18 FAMILY IN SARCOIDOSIS AND IDIOPATHIC PULMONARY FIBROSIS IS RELATED TO THE PRODUCTION OF SUPEROXIDE ANIONS BY THESE CELLS

This study was designed to investigate the expression and functional p roperties of Leukocyte adhesion molecules (LeuCAM; CD11/CD18 family) o n human alveolar macrophages (AM) from patients with sarcoidosis and i diopathic pulmonary fibrosis. Cells were obtained by bronchoalveolar l avage (BAL) from 17 patients with sarcoidosis (SA), 15 with idiopathic pulmonary fibrosis (IPF), and 14 nonsmokers (NS). Expression of LeuCA M on freshly isolated cells was studied using the peroxidase- antipero xidase method with monoclonal antibodies (MoAb) detecting CD11a, CD11b , CD11c, and CD18. The functional properties of the adhesion molecules were studied by measuring superoxide anion production (O2-) of SA and IPF AM after blocking the CD18 molecule by an MoAb. Compared with non smokers, the samples from SA and IPF patients contained an increased n umber of AM expressing CD11a, CD11b, CD11c, and CD18 (all p < 0.008), which was correlated to the number of AM/ml BAL (p < 0.008). Spontaneo us O2- secretion of AM was higher in SA (6.4 +/- 1.2 nMO2-/10(6) AM/12 0 min) and IPF (12.0 +/- 1.1 nMO2-/10(6) AM/120 min) compared with NS (2.5 +/-0.2 nMO2-/10(6) AM/120 min) (both p < 0.008). Incubation of th e AM with the MoAb anti-CD18 reduced the spontaneous O2- release from SA AM by 52 +/- 8% and from IPF AM by 49 +/- 3% but did not influence O2- release from NS AM (92 +/- 4%). Our data indicate that the increas ed expression of LeuCAM on AM in subjects with SA and IPF seems to be involved in the increased O2- production of these cells in both diseas es.