Objectives: Tumour necrosis factor alpha (TNFalpha) is a key cytokine involved in granuloma formation of sarcoidosis. Since soluble TNF receptors (sTNF-R) are known to inhibit TNF effects, we were interested in whether they are elevated in the serum of sarcoidosis patients.
Methods: We determined serum levels of sTNF-R I (55 kDa) and sTNF-R II (75 kDa) in 49 patients with sarcoidosis and 22 controls. The clinical course of the disease was re-evaluated in a follow-up after (mean +/- SE) 6.8 +/- 6.6 months.
Results: sTNF-R I (3.1 +/- 1.1 ng mL-1, P < 0.05) and sTNF-R II (5.5 +/- 2.7 ng mL-1, P < 0.0005) were significantly elevated in sarcoidosis compared with controls (2.4 +/- 0.7 and 3.0 +/- 1.3 ng mL-1, respectively). Interestingly, both sTNF receptors were significantly higher in the serum of patients with active compared with inactive sarcoidosis (P < 0.005 and P < 0.0005, respectively). Furthermore, serum sTNF-R II levels were significantly higher in sarcoidosis patients with advanced radiological types II and III. In 10 patients, serum sTNF-R levels were obtained before and after systemic corticosteroid therapy and we observed a significant decrease of sTNF-R II (P < 0.02), whereas sTNF-R I levels were not reduced significantly.
Conclusions: Both types of sTNF receptors are elevated in the serum of sarcoidosis patients with active disease, but only the sTNF-R II seems to be useful for monitoring the inflammatory activity of the disease.