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).