By using surface markers (CD14, CD163, CD68, CD32, CD64, CD200R, CD80) on ST macrophages from RA and PsA patients, that study found a mixed M1-proinflammatory/M2-anti-inflammatory macrophage phenotype, with M1 predominance in RA and IL-10-expressing macrophages in SpA, including PsA (16). Here, FCGR1A is linked to rheumatoid arthritis.