[Mechanism of sarcoid granuloma formation--participation of cytokines and chemokines]

Abstract

In sarcoidosis, unknown antigen(s) causes Th1-mediated granulomatous inflammation with cytokines such as IFN gamma and IL-12, initially. IL-16, IL-8, IP-10 and RANTES are participated in the accumulation of CD4+ T cell. For the chemotaxis of macrophages and monocytes, MCP-1, MIP1-alpha and RANTES are participated. Local proliferation of T cell is induced by IL-2 and IL-15 and that of macrophage/monocyte lineage is done by M-CSF, GM-CSF and G-CSF. Removal of the causative antigen(s) allows immune-suppressive cytokines such as TGF beta to downregulate the immune response and granuloma formation. Failure of removal of causative antigen(s) can induce prolonged existence of granuloma and irreversible fibrosis.