CD81 Specific Neutra™ Antibody Products

CD81 (Cluster of Differentiation 81, aliases TSPAN28, CVID6, TAPA1) is a cell surface protein (~26 kDa) belonging to an evolutionarily conserved tetraspanin family. It is mainly expressed in endothelial, hemopoietic, and epithelial cells, participating in multiple regulations on immune cells. It consists of four transmembrane domains.

Its Gene ID: 975, UniProtKB ID: P60033, and OMIM ID: 186845.

Fig.1 Structure of CD81.Distributed under CC BY-SA 3.0, from Wiki, without modification.

CD81 Functions and Signaling Pathways

As is initially identified by screening monoclonal antibodies (mAbs) elicited for their direct effects against B cell lymphoma proliferation in humans, CD81 plays a critical role in B cell physiology. CD81 is necessary for the intracellular trafficking of CD19 to the cell membrane to form the CD19-CD21-CD81 complex, a B cell coreceptor, at tetraspanin-enriched signaling microdomains, and facilitates the assembly of CD19-CR2/CD21, thus decreasing the threshold to trigger B-cell clonal expansion and antibody production. Besides, CD81 also enhances the B cell adhesion to the vessel wall, by promoting contacts of multivalent VLA-4 within subsecond integrin occupancy.

In T cells, CD81 is closely involved with the temporal progression of the immune synapse and the permanency of CD3 in the contact area on cell surfaces, contributing to long-lasting T-cell receptor-CD3-mediated signaling, thus regulating the activation of T-cells. In nature killer (NK) cells, CD81 induces phosphorylation of the ERM protein by crosslinking, and co-localizes with phosphorylated ERM at the uropod, partaking in the regulation of cell polarization and migration toward chemoattractants.

In addition, CD81 exerts regulation effects on virus infection. CD81 partakes in the assembly of both human immunodeficiency virus and influenza A virus on the cell surfaces, which is crucial for the entry of hepatitis C virus into hepatocytes. It is demonstrated that CD81 takes part in the activation of the Raf/MEK/ERK signaling cascade, and subsequently modulates post-entry activities of the viruses.

Fig.2 Schematic model depicting the subcellular localization of CD81 during virus infection.¹

Antibodies Targeting CD81

The essential and diverse roles that CD81 plays in many immune events and diseases make it emerge as a candidate target in preclinical/clinical research, therapeutic regimens, and drug development. It has been reported that a mAb targeting CD81 inhibits the growth of B cell lymphoma in a xenograft model as effectively as an antibody against CD20 approved by the FDA, which serves as a standard treatment for B cell lymphoma. What's more, compared to the anti-CD20 mAb, which damages malignant B cells as well as normal cells, the anti-CD81 mAb more precisely kills human lymphoma cells while sparing the normal lymphoid cells in the tumor microenvironment, exhibiting a better safety profile and providing optimized strategies for B cell lymphoma treatment.

Creative Biolabs offers different anti-CD81 antibody products. These antibodies are recombinantly expressed and could be used for various purposes. Customization of CD81-based neutralizing antibodies is also available for you here.

REFERENCE

1. Florin, Luise, and Thorsten Lang. "Tetraspanin assemblies in virus infection." Frontiers in immunology 9 (2018): 364425. Under open access license CC BY 4.0, without modification.