Description: The 1D6-CD81 monoclonal antibody reacts with human CD81, which is also known as Target of Anti-Proliferative Ab-1 (TAPA-1). A member of the tetraspanin superfamily of transmembrane proteins, CD81 is widely expressed on immune cells such as B, T, and NK cells, monocytes, and eosinophils. Studies suggest that the highest expression of CD81 can be found on germinal center B cells. On B cells, CD81 exists in a complex with CD19, CD21, and Leu13. CD81 plays a role in segregating the CD19/CD21-B cell receptor complexes to lipid rafts to activate signal transduction. Finally, CD81 is a receptor for hepatitis C virus.