Proapoptotic BH3-only protein Bim is essential for developmentally programmed death of germinal center-derived memory B cells and antibody-forming cells.
T cell-dependent B-cell immune responses induce germinal centers that are sites for expansion, diversification, and selection of antigen-specific B cells. During the immune response, antigen-specific B cells are removed in a process that favors the retention of cells with improved affinity for antigen, a cell death process inhibited by excess Bcl-2. In this study, we examined the role of the BH3-only protein Bim, an initiator of apoptosis in the Bcl-2-regulated pathway, in the programmed cell death accompanying an immune response. After immunization, Bim-deficient mice showed persistence of both memory B cells lacking affinity-enhancing mutations in their immunoglobulin genes and antibody-forming cells secreting low-affinity antibodies. This was accompanied by enhanced survival of both cell types in culture. We have identified for the first time the physiologic mechanisms for killing low-affinity antibody-expressing B cells in an immune response and have shown this to be dependent on the BH3-only protein Bim.
Fischer
Silke F
SF
The Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia.
Bouillet
Philippe
P
O'Donnell
Kristy
K
Light
Amanda
A
Tarlinton
David M
DM
Strasser
Andreas
A
D000818:Animals; D000915:Antibody Affinity / Q000235:genetics / Q000276:immunology; D017209:Apoptosis / Q000235:genetics / Q000276:immunology*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D000072224:Bcl-2-Like Protein 11; D002470:Cell Survival / Q000235:genetics / Q000276:immunology; D018858:Germinal Center / Q000166:cytology / Q000276:immunology*; D007114:Immunization; D007156:Immunologic Memory / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000276:immunology*; D027041:Somatic Hypermutation, Immunoglobulin / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology
D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; C000606776:Bcl2l11 protein, mouse; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins