To investigate if macrophages were one of the major FcγR expressing cells in the RA joints, RA synovia was double stained with a PE-labelled anti-CD163 (a macrophage specific marker) mAb and an alexa green-labelled anti-FcγRI, FcγRII, FcγRIIb or FcγRIII mAb. The gene discussed is FCGR2A; the disease is rheumatoid arthritis.