Th1 cells, defined by the production of IFN-γ and the expression of the transcription factor T-bet, are involved in cell-mediated immunity and are important for immunity against intracellular pathogens while being associated with the pathogenesis of autoimmune diseases such as SLE, multiple sclerosis, and rheumatoid arthritis [67]. This evidence concerns the gene IFNG and rheumatoid arthritis.