CSF1 and rheumatoid arthritis: Our data might suggest that in CIA, CSF-1 plays an important role in promoting the differentiation and survival of mature monocytes in the periphery before or as they are entering the inflamed tissue, as observed in certain murine models of lung and peritoneal inflammation [6], while in RA synovial explants, synovial macrophages are no longer dependent upon CSF-1 alone.