Osteopontin is associated with T cells in sarcoid granulomas and has T cell adhesive and cytokine-like properties in vitro
Sarcoidosis is a systemic disease characterized by the accumulation of activated T cells and widespread granuloma formation. In addition, individual genetic predisposition appears to be important in this disease. Osteopontin, a noncollagenous matrix protein produced by macrophages and T lymphocytes, is expressed in the granulomas of tuberculosis, and is associated with genetic susceptibility to intracellular infection. The function of osteopontin in these T cell-mediated responses is unknown. We sought to elucidate the role of osteopontin in granulomatous inflammation by characterizing its expression in different stages of sarcoidosis and its effector function on T cells in vitro. Lymphocyte-associated expression of osteopontin in sarcoidosis was demonstrated by immunohistochemistry, and its expression correlated with granuloma maturity. In addition, osteopontin induced T cell chemotaxis, supported T cell adhesion (an effect enhanced by thrombin cleavage of osteopontin), and costimulated T cell proliferation. These results suggest a novel mechanism by which osteopontin and thrombin modulate T cell recruitment and activation in granulomatous inflammation.
Journal of Immunology
O'Regan, A., Chupp, G., Lowry, J., Goetschkes, M., Mulligan, N., & Berman, J. (1999). Osteopontin is associated with T cells in sarcoid granulomas and has T cell adhesive and cytokine-like properties in vitro. Journal of Immunology, 162 (2), 1024-1031. Retrieved from https://digitalcommons.memphis.edu/facpubs/8311