Cluster of differentiation 35 (CD35), also named as erythrocyte complement receptor 1 (CR1) is a cell membrane-bound, monomeric glycoprotein and its primary function is to serve as the cellular receptor for C3b and C4b, the most important components of the complement system leading to clearance of foreign macromolecules. CD35 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 leukocytes 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. CD35 is a mature B-lymphocyte marker, and Anti-CD35 reacts positively with normal and tumorous follicular dendritic reticulum cells.