CD4 and sarcoidosis: In sarcoidosis, the interaction between antigen presenting cells (APCs) and an unknown antigen(s) leads to a polarized T-helper 1 (Th1) CD4+ response including production of Th1 cytokines such as interferon-gamma (IFN-γ), tumor necrosis factor-α (TNF-α) and interleukin-2 (IL-2) [1], and the formation of granulomas.