CD4 and rheumatoid arthritis: Given the elevated level of IL-1β in RA synovial fluid and an important role of Th17 responses in RA pathogenesis (Kim et al., 2016; Kay and Calabrese, 2004), impaired induction of IL-1RII may be associated with modulation of IL-17 production in CD4+ T cells of RA patients under chronic autoreactive situations.