Identification of membrane antigens in granulocytes and colonic carcinoma cells by a monoclonal antibody specific for biliary glycoprotein, a member of the carcinoembryonic antigen family.

The gene coding for 'biliary glycoprotein (BGP)' is a member of the carcinoembryonic antigen (CEA) gene family. A monoclonal antibody (MAb) was induced against a BGP-preparation isolated from human bile. The antibody did not crossreact with the carcinoembryonic antigen (CEA) and different non-specific crossreacting antigens. The anti-BGP MAb was used to identify BGP-related antigens in membrane extracts from granulocytes and the colonic carcinoma cell line HT-29. In granulocyte membranes, a single antigen of Mr 160,000 was bound. In membranes from HT-29 cells, a main antigen of Mr 85,000 was present. At high antigen concentration, an additional antigen of Mr 115,000 was identified. Since several transcripts of the BGP gene have been identified, the different BGP related antigens are probably products of alternatively spliced mRNAs.