Plasma level of interferon γ induced protein 10 is a marker of sarcoidosis disease activity.

RATIONALE

Sarcoidosis is an idiopathic granulomatous disorder with heterogeneous clinical manifestations and variable prognosis. Monitoring disease activity is important to identify patients requiring treatment. Several cytokines have previously been shown to be elevated in the serum of patients with sarcoidosis and may be useful biomarkers of disease activity.

OBJECTIVES

To identify novel biomarkers of sarcoidosis disease activity. To identify the relationship between plasma cytokines, disease severity and prognosis.

METHODS

The study was approved by the institutional review board. Plasma concentration of 19 cytokines was measured in 112 subjects with chronic sarcoidosis and 52 matched controls, using the bead-based Milliplex xMAP multiplex technology. Plasma levels of individual cytokines were compared between the two groups, and between the groups with clinically active vs. inactive disease. Sensitivity, specificity and receiver operating characteristics curves were used to evaluate biomarker performance. Linear regression analyses were performed to identify associations between cytokine levels, pulmonary function tests and changes in pulmonary function.

MEASUREMENTS AND MAIN RESULTS

Subjects with sarcoidosis had higher plasma levels of interferon gamma induced protein 10 (IP-10) and tumor necrosis factor α (TNFα). IP-10 had the highest sensitivity and specificity in identifying active disease. Higher levels of IP-10 and TNFα were associated with greater disease severity and better prognosis.

CONCLUSIONS

IP-10 is a potentially useful biomarker of sarcoidosis and its severity.