Soluble intercellular adhesion molecule 1 (sICAM-1) in bronchoalveolar lavage (BAL) cell cultures and in the circulation of patients with tuberculosis, hypersensitivity pneumonitis and sarcoidosis.

Intercellular adhesion molecule-1 (ICAM-1) plays an important role in inflammatory diseases. It is believed that its soluble form (sICAM-1) might be a serum parameter of inflammatory activity with possible relevance in granulomatous disorders. To evaluate this role we measured sICAM-1 by ELISA in serum and shedding of this molecule by BAL cells in patients with granulomatous lung diseases (pulmonary tuberculosis (TB), hypersensitivity pneumonitis (HSP), pulmonary sarcoidosis (PS), and controls). Serum concentrations of sICAM-1 in patients with TB (496.9 +/- 49.7 ng/ml), with HSP (636.5 +/- 85.9.8 ng/ml), and with PS (588.3 +/- 72.2 ng/ml) were significantly increased compared to controls (275.7 +/- 33.1 ng/ml). Spontaneous release of sICAM-1 by BAL cells differed among patient groups (TB: 9.3 +/- 1.7; HSP: 17.5 +/- 1.4; PS: 9.7 +/- 1.5 ng/ml), however, exceeding that of controls significantly (3.8 +/- 0.6 ng/ml). No correlations between the circulating level and the shedding of this molecule by BAL cells were observed within the groups. Significant correlations between serum sICAM-1 and serum tumor necrosis factor alpha (TNFalpha) level were observed in patients with HSP and TB. Kinetic cell culture experiments with BAL cells revealed a dissociation in sICAM-1 shedding and TNFalpha release. After stimulation rapid upregulation of both molecules (5 h) was followed by a cessation of TNFalpha production at 28 h. sICAM-1 shedding, however, was maintained over 2 days. Our results evidence that the circulating pool of sICAM-1, as well as the shedding of this molecule by BAL cells reflect the activity of cells in the inflammatory processes of granulomatous diseases.