MRC1 and temporal arteritis: GM-CSF highly regulates CD206 expression by macrophages and GM-CSF is in close vicinity with these CD206+/MMP-9+ macrophages suggesting that GM-CSF may drive the tissue destructive phenotype macrophages in GCA.[36] A monoclonal antibody to GM-CSF receptor-α, mavrilimumab in a proof-of-concept study (NCT03827018) was tested for its efficacy and GC sparing capacity in 26-week tapering of prednisone.