Human cytokine synthesis inhibitory factor (CSIF), more commonly known as IL-10 functions to inhibit the formation of pro-inflammatory cytokines such as TNF-α, IL-1α, IL-1β, IL-6, IL-8, IL-12 and GM-CSF, as well as reducing the expression of HLA-DR and B7 molecules subsequently inhibiting macrophage antigen presentation in the synovial fluid and peripheral blood of RA patients, which in turn attenuates inflammation (235). Here, TNF is linked to rheumatoid arthritis.