High Plasma Osteopontin Level and Its Relationship with Interleukin-12–mediated Type 1 T Helper Cell Response in Tuberculosis

Osteopontin (OPN, also known as Eta-1), a noncollagenous matrix protein produced by macrophages and T lymphocytes, is expressed in granulomatous lesions caused by Mycobacterium tuberculosis infection. In the present study, we compared plasma concentrations of OPN in patients with active pulmonary tuberculosis with those of healthy control subjects and patients with sarcoidosis, another disease associated with granuloma formation. Plasma OPN levels were significantly higher in patients with tuberculosis (n = 48) than in control subjects (n = 34) and patients with sarcoidosis (n = 20). OPN levels correlated well with severity of pulmonary tuberculosis, as indicated by the size of lung lesions on chest X-ray films. Furthermore, chemotherapy resulted in a significant fall in plasma OPN levels. In patients with tuberculosis, plasma OPN concentrations correlated significantly with those of interleukin (IL)-12. In vitro experiments showed that OPN production by peripheral blood mononuclear cells infected with My...