FCGR1A and rheumatoid arthritis: To develop an imaging technique for CD64 in vivo, we conjugated an anti-CD64 antibody with IRDye 800CW and diethylenetriamine penta-acetic acid (DTPA; used for 111In labeling) and tested its imaging potential in severe combined immunodeficient (SCID) mice implanted with human RA synovium explants [8, 9].