title: Immunoelectron microscopy studies on the modulation of common acute lymphoblastic leukemia antigen (CALLA) on NALM-6 cells: delineation of intracellular transport.
abstract: Even though much is known about the presence of the common acute lymphoblastic leukemia antigen (CALLA) with respect to its distribution in hematopoietic and non-hematopoietic tissues, its functional role in lymphoid cells is as yet unknown. Given the fact that CALLA is completely modulated on the surface of lymphoid cells, we have employed pre-embedding immunogold techniques at electron-microscopical level and demonstrated that J5 monoclonal antibody (MoAb)-mediated modulation of CALLA expression on the lymphoblastic cell line NALM-6 is a specific, rapid process, closely resembling receptor-mediated endocytosis. Furthermore, it was found that CALLA was internalized through plasmalemmal pits and cytoplasmic vesicles and processed intracellularly in multivesicular bodies and secondary lysosomes. In contrast, HLA-DR antigen remained at the cell surface upon contact with specific MoAb. These data suggest that CALLA might be a receptor for a hitherto unknown signal molecule.
authors.affiliation: University Department of Medicine and Hematology, Aarhus Amtssygehus, Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Pulczynski
authors.forename: A M
authors.initials: AM
authors.lastname: Boesen
authors.forename: O M
authors.initials: OM
authors.lastname: Jensen
authors.forename: J
authors.initials: J
authors.lastname: Ellegaard
authors.forename: P
authors.initials: P
authors.lastname: Hokland
mesh_terms: D000943:Antigens, Differentiation / Q000378:metabolism*; D000951:Antigens, Neoplasm / Q000378:metabolism*; D001692:Biological Transport; D002451:Cell Compartmentation; D004705:Endocytosis; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D007150:Immunohistochemistry; D008854:Microscopy, Electron; D015260:Neprilysin; D015452:Precursor B-Cell Lymphoblastic Leukemia-Lymphoma / Q000378:metabolism*; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D000943:Antigens, Differentiation; D000951:Antigens, Neoplasm; D015260:Neprilysin