[Co-stimulating effect of extracellular matrix proteins on T lymphocyte proliferation in patients with sarcoidosis....

Although very little is known about the aetiology of sarcoidosis, its immunopathogenesis is now better known. The interaction of alveolar macrophages and T cells may play a role in the pathomechanism of the disease. To infiltrate the tissue, lymphocytes have to migrate through the subendothelial basement membrane and interstitium, rich in extracellular matrix (ECM). The interaction of lymphocytes with proteins of the ECM may play an important role in the migration, accumulation and activation of these cells. The aim of our study was to estimate the ability of the ECM components (collagen I, collagen IV and fibronectin) to co-stimulate T-cells in patients with sarcoidosis. The peripheral blood was obtained from 14 sarcoid patients. The disease was confirmed histologically in 9 cases and in 5 patients on clinical grounds. In radiological findings 4 persons were at the first stage of the disease, 4 at the second, in three cases interstitial changes were found and in three patients, the fibrosis on the X-ray was noticed. No one of those patients were treated with steroids during last 2 months. Normal peripheral blood T cells are strongly co-stimulated by ECM proteins. In contrast, lymphocytes from patients with sarcoidosis were inhibited by the ECM proteins. The mean co-stimulation ratios (OKT3 + ECM proteins:OKT3 alone) were significantly lower for all ECM proteins (collagen I: p < 0.00009; collagen IV: p < 0.02; fibronectin: p < 0.04). Our data shed a new light on the nature of sarcoidosis associated immunodeficiency and suggest that disturbed T cells: ECM interactions may play a role in the pathogenesis.