title: Internalized membrane immunoglobulin meets intracytoplasmic DR antigen in human B lymphoblastoid cells.
abstract: The important role of type II antigens of the major histocompatibility complex (Ia and DR) in the antigen presentation and in the antigen-specific cooperation between T and B cells is by now firmly established. Human B lymphoblastoid lines MWE and BL were stained with different fluoresceinated anti-DR antibodies. Not only surface but intracytoplasmic DR structures were brightly stained. The intracellular stain accumulated in a cluster close to the nucleus. Different specificity controls were performed. MWE and BL cells quickly internalize membrane IgM if cross-linked by corresponding antibodies. The intracellular location of the vesicles containing these complexes showed substantial coincidence with DR-positive structures in the paranuclear location. It is speculated that IgM-ligand complexes meet internal DR molecules and are both reexpressed on the plasma membrane to be recognized by primed T cells.
mesh_terms: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D000951:Antigens, Neoplasm / Q000276:immunology*; D000954:Antigens, Surface / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology; D005455:Fluorescent Antibody Technique; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D006801:Humans; D007075:Immunoglobulin M / Q000032:analysis; D007945:Leukemia, Lymphoid / Q000276:immunology*; D008285:Major Histocompatibility Complex; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II; D007075:Immunoglobulin M