What is the pathogenesis of sarcoidosis?

Updated: Sep 15, 2020
  • Author: Nader Kamangar, MD, FACP, FCCP, FCCM; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Answer

T cells play a central role in the development of sarcoidosis, as they likely propagate an excessive cellular immune reaction. For example, there is an accumulation of CD4 cells accompanied by the release of interleukin (IL)–2 at sites of disease activity. This may manifest clinically by an inverted CD4/CD8 ratio. Pulmonary sarcoidosis is frequently characterized by a CD4+/CD8+ ratio of at least 3.5 in bronchoalveolar lavage fluid (BALF), although up to 40% of the cases present a normal or even decreased ratio, thus limiting its diagnostic value. [17] Increased production of TH1 cytokines, such as interferon, is also a feature.

Moreover, both tumor necrosis factor (TNF) and TNF receptors are increased in this disease. The importance of TNF in propagating inflammation in sarcoidosis has been demonstrated by the efficacy of anti-TNF agents, such as pentoxifylline [18] and infliximab, [10, 11] in treating this disease.

In addition to T cells, B cells also play a role. There is evidence of B cell hyperreactivity with immunoglobulin production.


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