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

Area of Science:

• Immunology
• Pulmonology
• Biochemistry

Background:

• Sarcoidosis involves a T helper 1 (Th1) immune response.
• Interleukin-12 (IL-12) is upregulated at disease sites in sarcoidosis.
• The clinical utility of circulating IL-12 in sarcoidosis requires investigation.

Purpose of the Study:

• To assess the clinical usefulness of serum interleukin-12 (IL-12) concentrations in pulmonary sarcoidosis.
• To correlate IL-12 levels with disease activity markers and T helper 1 (Th1) responses.

Main Methods:

• Serum IL-12 p40 and p70 concentrations were measured using ELISA in 45 sarcoidosis patients and 18 controls.
• Immunohistochemistry was performed on lung and lymph node samples.
• Correlations with interferon-gamma (IFN-gamma), angiotensin-converting enzyme (ACE), lysozyme, and 67Ga scans were analyzed.

Main Results:

• Serum IL-12 p40 was detectable in all subjects and significantly higher in sarcoidosis patients than controls.
• Elevated IL-12 p40 correlated positively with serum IFN-gamma, ACE, and lysozyme levels.
• IL-12 p40 was expressed in epithelioid cells and macrophages in sarcoid tissues; IL-12 p70 bioactivity was undetectable in sera.

Conclusions:

• Serum IL-12 p40 is significantly elevated in pulmonary sarcoidosis.
• Serum IL-12 p40 serves as a useful clinical marker for disease activity and Th1 response in sarcoidosis.