CD4 and Takayasu arteritis: Interferon -γ is a major player in pathogenesis of TA and a recent study by Ren et al. (44) reported that, CD8+ T lymphocytes were a significant source of interferon -γ, with peripheral blood showing higher number of CD3+CD8+IFN-γ+cells and a lower ratio of CD3+CD4+IFN-γ+/ CD3+CD8+IFN-γ+ in TA compared to controls.