CSF2 and rheumatoid arthritis: While the role of GM-CSF in JIA is not as well studied as that in RA [53], the frequency of GM-CSF-producing T helper cells was significantly enriched among SF mononuclear cells, and the culturing of Th17 cells in the presence of IL-12 resulted in upregulation of GM-CSF and IFNγ, recapitulating the phenotype of GM-CSF-expressing cells within the JIA joints [54].