|Detection of CD35 in Human Whole Blood Lymphocytes by Flow Cytometry. Human whole blood lymphocytes were stained with Mouse Anti-Human CD19 Fluorescein‑conjugated Monoclonal Antibody (Catalog # FAB4867F) and either (A) Mouse Anti-Human CD35 PE‑conjugated Monoclonal Antibody (Catalog # FAB5748P) or (B) Mouse IgG1 Phycoerythrin Isotype Control (Catalog # IC002P). View our protocol for Staining Membrane-associated Proteins.|
CD35, also known as Complement Receptor 1 (CR1), is a 220-300 kDa type I transmembrane glycoprotein member of the RCA (Regulators of Complement Activation) family of proteins. CD35 binds and internalizes particles and immune complexes that are opsonized with MBL or complement components C3b, C3i, C4b, or C1q. CD35 additionally protects the cell from complement-mediated lysis by serving as a cofactor for Factor I and inhibiting the C3 and C5 convertases. The extracellular domain (ECD) of human CD35 contains 30 tandem SCR/SUSHI repeats. A soluble form of the CD35 ECD circulates in the serum. There do not appear to be any splice variants associated with the CD35 gene. A mouse ortholog of human CD35 has not been described, although alternate splicing of mouse CD21/CR2 generates a protein with homology to some SCR repeats of human CD35. Cell surface CD35 is expressed on selective cells such as follicular dendritic cells, erythrocytes, astrocytes, kidney podocytes, neutrophils, and eosinophils.