The molecular mechanism in activation-induced cell death of an Ag-reactive B cell clone.
TPA-1 is a subclone of B cell hybridomas established by somatic hybridization using B cells of A/J mice immunized with TNP-LPS, and expresses a receptor for TNP on the cell membrane. The present study showed that TPA-1 was induced to apoptotic cell death upon treatment with TNP-BSA. Therefore, TPA-1 is considered to provide a good model for the study on activation-induced cell death of mature B cells induced by soluble antigen. TNP-BSA treatment caused the generation of a large amount of intracellular reactive oxygen species (ROS) of TPA-1, and the addition of the monovalent thiol-reactive compound: monochlorobimane (MCB) rescued it from apoptosis as well as the antioxidant reagent: N-acetyl-L-cysteine. Furthermore, MCB markedly inhibited the generation of ROS and prevented the disruption of mitochondrial membrane potential that was induced by TNP-BSA treatment. In addition, it counteracted the effect of TNP-BSA on the expression of the Bcl-2 family, resulting in down-regulation of Bax and Bad and up-regulation of Bcl-XL. Taken together, these results suggest strongly that oxidative stress of mitochondria may be involved directly in apoptotic cell death by engagement of antigen receptors on mature B cells with soluble antigen.
Hamano
T
T
Division of Clinical Immunology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan. teru-h@hyo-med.ac.jp
Iwasaki
T
T
Ogata
A
A
Hashimoto
N
N
Kakishita
E
E
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D001402:B-Lymphocytes / Q000166:cytology / Q000187:drug effects*; D002352:Carrier Proteins / Q000096:biosynthesis; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D007424:Intracellular Fluid / Q000378:metabolism; D008564:Membrane Potentials; D051379:Mice; D008805:Mice, Inbred A; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012710:Serum Albumin, Bovine / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D051028:bcl-2-Associated X Protein; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein
D000590:Amino Acid Chloromethyl Ketones; C494820:Bad protein, mouse; C494827:Bax protein, mouse; C494812:Bcl2l1 protein, mouse; D002352:Carrier Proteins; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D051028:bcl-2-Associated X Protein; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C038601:trinitrophenyl-bovine serum albumin; D012710:Serum Albumin, Bovine