Increased circulating interleukin-12 (IL-12) p40 in pulmonary sarcoidosis

Open Access
Publisher Website
Google Scholar
Abstract
In sarcoidosis, a T helper 1 (Th1) response is an essential event and the up‐regulation of interleukin‐12 (IL‐12) has been detected in affected disease sites. In order to investigate the clinical usefulness of circulating IL‐12, we measured the serum concentrations of IL‐12 by ELISA and performed immunohistochemistry using specific MoAbs for IL‐12 in the lungs and scalene lymph nodes of patients with sarcoidosis. The serum concentration of IL‐12 p40 was detectable in all 45 patients with pulmonary sarcoidosis and 18 normal controls, whereas that of IL‐12 p70 was undetectable. The serum concentrations of IL‐12 p40 in pulmonary sarcoidosis were significantly higher than those of the normal controls, especially in cases with abnormal intrathoracic findings detected by chest roentogenogram. The serum concentrations of interferon‐γ (IFN‐γ) also increased compared with those of normal controls and there was a significant positive correlation between the serum concentrations of IL‐12 p40 and IFN‐γ. Furthermore, serum angiotensin‐converting enzyme (ACE) and lysozyme, which are known to be useful markers for disease activity in sarcoidosis, correlated well with the serum concentrations of IL‐12 p40. The positive 67Ga scan group (for lung field) had significantly elevated serum IL‐12 p40 levels compared with those of the negative group. No bioactivity of IL‐12 p70 was detected in three sarcoid cases sera by using the IL‐12 responsive cell line. Finally, the immunohistochemical approach revealed that IL‐12 p40 was expressed in the epithelioid cells and macrophages of sarcoid lungs and lymph nodes. We concluded that the production of IL‐12 p40 was far greater in the sera and we have demonstrated this to be a useful clinical marker for disease activity and the Th1 response in pulmonary sarcoidosis.

This publication has 24 references indexed in Scilit: