TNF and sarcoidosis: The primary regulator of the innate immune response in sarcoidosis was the alveolar macrophage, which both produced pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), contributing to the production of granulomatous lesions, and acted as an antigen-presenting cell (APC) interacting with T cells via human leucocyte antigen (HLA) molecules and T cell receptors (21, 22).