Increased expression of leukocyte function associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) by alveolar macrophages of patients with pulmonary sarcoidosis

Leukocyte function associated antigen-1 (LFA-1) and its ligand intercellular adhesion molecule-1 (ICAM-1) are cell adhesion molecules that play an important role in the capacity of mononuclear phagocytes (MPs) to present antigens to T lymphocytes. Since in pulmonary sarcoidosis (PS) this capacity is increased at sites of disease activity, we studied the expression of LFA-1 and ICAM-1 on peripheral blood monocytes (BMs) and alveolar macrophages (AM) obtained by bronchoalveolar lavage (BAL) from normal subjects (n=7) and patients with PS (n=14). To accomplish this, immunocytochemical stainings were made on cytocentrifuge preparations using anti-LFA-1 (anti-CD 11a) and anti-ICAM-1 (anti-CD 54) monoclonal antibodies (MoAbs). Normal and sarcoid BMs displayed a high percentage of positivity with both MoAbs with no difference between study groups (LFA-1: control BM 87.8±8.8 percent; sarcoid BM 84.7±9.5 percent; ICAM-1: control BM 80.8±10 percent; sarcoid BM 88.0±4.2 percent; p=NS for all comparisons). In both groups the percentage of cells expressing LFA-1 and ICAM-1 molecules among AMs was lower than among autologous BMs (LFA-1: control AM 46.5±13.2 percent, p<0.001 vs control BM; sarcoid AM 64.2±15.9; p<0.001 vs sarcoid BM) (ICAM-1: control AM 42.7±8.5 percent, p<0.001 vs control BM; sarcoid AM 72.1±10.6, p<0.001 vs sarcoid BM). AMs from patients with PS showed a higher degree of positivity for LFA-1 and ICAM-1 than normal AMs (p<0.02 and p<0.001, respectively). The positivity for LFA-1 and ICAM-1 molecules on sarcoid AMs was not correlated with the positivity for two different BM-associated markers (ie, the CD 11b and the CD 14 molecules) and was not correlated with the percentage of T lymphocytes in BAL, selected as a marker of the intensity of the alveolitis. These results suggest that the increased ability of sarcoid AMs to induce the proliferation of T lymphocytes may be related, at least in part, to the increased expression of LFA-1 and ICAM-1 molecules on their surfaces.