Pathophysiology
The cause of sarcoidosis is not yet well understood but an antigen-triggered, cell-mediated immune response is known to initiate the sarcoidosis disease process (2). Genetic susceptibility and specific environmental or infectious triggers combine to perpetuate a chronic cell-mediated immunological response (3). T lymphocytes and macrophages accumulate and produce inflammatory mediators such as cytokines (particularly TNF-alpha, IL-12 and IL-18), which lead to the formation of granulomata (2, 4). Certain HLA haplotypes are suggested to predispose to the disease and bacterial triggers have also been proposed, although evidence for this remains inconclusive (1, 2, 5).