Immunoelectron microscopy studies on the modulation of common acute lymphoblastic leukemia antigen (CALLA) on NALM-6 cells: delineation of intracellular transport.
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.
Pulczynski
S
S
University Department of Medicine and Hematology, Aarhus Amtssygehus, Denmark.
Boesen
A M
AM
Jensen
O M
OM
Ellegaard
J
J
Hokland
P
P
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
D000943:Antigens, Differentiation; D000951:Antigens, Neoplasm; D015260:Neprilysin