Anti-Human CD21 (Clone Bu32) - FITC (C612-GRP)

CD21 (complement receptor type 2; CR2) is a type I membrane glycoprotein that functions as the receptor for complement C3 fragments iC3b, C3dg and C3d, low-affinity IgE receptor CD23, type I cytokine, interferon-alpha as well as the Epstein-Barr virus gp350/220 envelope protein 1, 2, 3 CD21 is part of a molecular complex that includes CD19, Leu 13 and TAPA-1 1 . CD21 enhances B cell proliferation and modulates the immune response 1 . By binding to C3d, CD21 links the innate complement-mediated immune response against pathogens and foreign antigens to the adaptive immune response 3 . Additionally, the CD19/CD21 complex functions synergistically with the B cell Ag receptor (BCR) to reduce the threshold for B cell activation. CD21 is also required for the extracellular trapping of HIV by lymph node cells, and disruption of this process reduces HIV reservoirs 4 . Furthermore, CD21 affects the ability of CD19-CAR-T cells to recognize malignant B cells that are CD19-positive and impairs its antitumor function 5 . Bu32 was produced in mouse at the University of Birmingham, England, and was shown to be specific to CD21 antigen via tests on cell lines, histological tissue sections, and blood cells 6, 7, 8, 9 . Bu32 was authenticated in the IVth and Vth International Leukocyte Workshops 9 .