Elevated Levels of Type II Soluble Tumor Necrosis Factor Receptors in the Bronchoalveolar Lavage Fluids of Patients with Sarcoidosis

Since tumor necrosis factor (TNF) is known to be involved in granuloma formation in sarcoidosis, and soluble TNF receptors (sTNF-Rs) inhibit TNF action in vivo, we evaluated the levels of sTNF-Rs in the bronchoalveolar lavage fluids (BALF) of 31 subjects using an enzyme-linked immunosorbent assay. Our group consisted of 13 patients with sarcoidosis (7 sarcoidosis patients who received no treatment and 6 who received corticosteroid therapy) and 18 control subjects (11 healthy nonsmokers and 7 asymptomatic smokers). Type II (75-kDa), but not type I (55 kDa) sTNF-R in BALF was elevated significantly in patients with sarcoidosis compared with the healthy nonsmokers (type I: 126.7 ± 17.6 pg/ml BALF vs 79.4 ± 16.5 pg/ml BALF, p > 0.05; type II: 98.3 ± 27.8 pg/ml BALF vs 26.7 ± 4.9 pg/ml BALF, p < 0.05). Although levels of type I sTNF-R in BALF from sarcoidosis patients were not correlated with any cellular profiles of BALF, concentrations of type II correlated significantly with the numbers of lymphocytes in BALF. We concluded that sTNF-R is a normal constituent of the epithelial lining fluids and that levels of type II sTNF-R are elevated significantly in the BALF from individuals with sarcoidosis. This suggests that sTNF-Rs may influence the local bioactivity of TNF and may also contribute to the pathogenesis of sarcoidosis. Accepted for publication: 7 November 1996