CD35, also known as complement receptor 1 (CR1), is a membrane-bound glycoprotein expressed on a variety of immune cells, including but not limited to B cells, monocytes, granulocytes, erythrocytes, and follicular dendritic cells, where it plays a key role in the regulation of complement activation and clearance of immune complexes. CD35 also presents on various non-immune cells such as erythrocytes.