title: Mechanisms of antigen receptor-dependent apoptosis of human B lymphoma cells probed with a panel of 27 monoclonal antibodies.
abstract: The present study has used a panel of 23 monoclonal antibodies to IgM and 4 to IgD in order to probe parameters influencing sIg-dependent apoptosis in an IgM/IgD-expressing Burkitt lymphoma line. No direct correlation was observed between the capacity of the different anti-mu to drive cells into apoptosis and either their domain specificity or their affinity for sIgM. There was, however, a direct correlation between the functional outcome and the ability of the monoclonal antibodies to elicit a rise in intracellular Ca2+. For apoptosis to occur, the Ca2+ response had to attain a threshold value of approximately 100 nM. A direct role for Ca2+ in the delivery of the apoptotic signal was demonstrated using thapsigargin to raise intracellular Ca2+ levels. Antigen receptor ligation was linked to Ca2+ increases by tyrosine kinases as revealed by direct analysis of protein tyrosine phosphorylation and the effects of selective protein tyrosine kinase-inhibiting tyrphostins. These findings reveal a central role for the antigen receptor-generated Ca2+ signal in driving apoptosis in human B lymphoma cells and stresses the need to use a panel of reagents when probing function with presumed ligand-mimetic monoclonal antibodies.
authors.affiliation: Department of Immunology, Medical School, University of Birmingham, Edgbaston, UK.
authors.forename: G
authors.initials: G
authors.lastname: Grafton
authors.forename: M
authors.initials: M
authors.lastname: Goodall
authors.forename: C D
authors.initials: CD
authors.lastname: Gregory
authors.forename: J
authors.initials: J
authors.lastname: Gordon
mesh_terms: D000911:Antibodies, Monoclonal; D017209:Apoptosis / Q000276:immunology* / Q000502:physiology; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D002051:Burkitt Lymphoma / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018604:Epitope Mapping; D006801:Humans; D007072:Immunoglobulin D / Q000378:metabolism; D007075:Immunoglobulin M / Q000378:metabolism; D007424:Intracellular Fluid / Q000378:metabolism; D007700:Kinetics; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011947:Receptors, Antigen, B-Cell / Q000276:immunology* / Q000378:metabolism; D015398:Signal Transduction; D019284:Thapsigargin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D004791:Enzyme Inhibitors; D007072:Immunoglobulin D; D007075:Immunoglobulin M; D011947:Receptors, Antigen, B-Cell; D019284:Thapsigargin; D011505:Protein-Tyrosine Kinases; D000252:Calcium-Transporting ATPases; D002118:Calcium