CD77/Gb3 [38.13]

CD77 (Gb3), also known as the Pk blood group antigen, Burkitt´s lymphoma associated antigen), or ceramide trihexoside, is a neutral glycosphingolipid composed of three carbohydrate molecules linked to a lipid moiety in the cell membrane (Gal-alpha1-4Gal-beta1-4Glc-beta1-Cer). It is a key differentiation marker for germinal center B cells (specifically centroblasts entering apoptosis and Burkitt’s lymphoma cells. It is highly expressed on endothelial cells especially in renal capillaries and select epithelial linings of the gastrointestinal tract. Pathological Accumulation: In Fabry disease, a genetic deficiency in α-galactosidase A causes CD77 to massively accumulate abnormally within lysosomes and extra-lysosomal space. CD77 is significantly overexpressed on the surface of several human cancers, including head and neck squamous cell carcinomas, gastric, pancreatic, and colorectal cancers. CD77 may be involved in elimination of germinal center B cells that fail to produce high affinity antibodies and serves as the primary cellular receptor for bacterial Shiga toxins and verotoxins.