IL17A and rheumatoid arthritis: Neurodegeneration in multiple sclerosis, synovial inflammation in rheumatoid arthritis, inflammatory bowl disease, and type I diabetes have all been shown to be in part mediated by IL-17A and IFN-γ (Toh and Miossec, 2007; Yamada et al., 2008; Uhlig and Powrie, 2009; Durant et al., 2010; Kaser et al., 2010).