CD35, also named as erythrocyte complement receptor 1 (CR1), is a member of the complement activation (RCA) family and is located in the ‘cluster RCA’ region of chromosome 1. CD35 mediates cellular binding to particles and immune complexes that have activated complement. CD35 is present on erythrocytes, various leucocytes and renal glomerular podocytes. In addition, plasma contains a soluble form of CR1 (Scr1). CD35 also can be detected on follicular dendritic cells. It is a marker for the diagnosis of follicular dendritic cell sarcoma.