Kinetics of the apoptotic response induced by anti-IgM engagement of the B cell receptor is dependent on the density of cell surface immunoglobulin M expression.
The effect of B cell receptor (BCR) density on anti-BCR-induced apoptosis was assessed in Ramos cell lines, expressing low, medium, or high levels of surface IgM (sIgM(LO), sIgM(MED), sIgM(HI)). All cells required a 6-mug/ml threshold of anti-IgM to elicit apoptosis. Anti-IgM treatment of sIgM(LO) cells induced growth inhibition and limited dose-independent apoptosis. Anti-IgM treatment of sIgM(MED) cells induced dose-independent death with a 32-h lag. Ligation of the BCR in the sIgM(HI) cells induced rapid apoptosis beginning by 6 h, which was dose-dependent. Secondary crosslinking reagents did not affect apoptosis, and this effect was independent of anti-IgM concentration, time, or sIgM density. These results suggest that the response to BCR engagement strongly depends on the cell surface receptor density.
Trujillo
Miguel A
MA
Department of Medicine, Division of Endocrinology, Mayo Clinic/Mayo Foundation, Rochester, Minnesota 55905, USA.
Eberhardt
Norman L
NL
D000888:Antibodies, Anti-Idiotypic / Q000494:pharmacology*; D017209:Apoptosis; D002051:Burkitt Lymphoma; D002455:Cell Division / Q000187:drug effects; D002462:Cell Membrane / Q000276:immunology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007075:Immunoglobulin M / Q000378:metabolism; D007700:Kinetics; D011947:Receptors, Antigen, B-Cell / Q000502:physiology*; D014407:Tumor Cells, Cultured
D000888:Antibodies, Anti-Idiotypic; D007075:Immunoglobulin M; D011947:Receptors, Antigen, B-Cell; C044203:anti-IgM