title: CD25 blockade protects T cells from activation-induced cell death (AICD) via maintenance of TOSO expression.
abstract: CD25 monoclonal antibody binding to the alpha-chain of the Interleukin-2 (IL-2) receptor, blocks high-affinity IL-2 binding, thereby preventing complete T-cell activation and being of ample importance in transplantation medicine and potentially the treatment of autoimmune disease. However, CD25 antibodies do not only block T-cell activation but also prevent activation-induced cell death (AICD) attributing a dual function to IL-2. In this study, the modulation of the genomic expression profile of human peripheral blood mononuclear cells (PBMC) with therapeutic concentrations of humanized anti-CD25 mAb was investigated. PBMC were stimulated with CD3 antibody OKT-3 together with recombinant IL-2 in the absence or presence of anti-CD25 mAb. RNA was extracted and subjected to microarray analysis on U133A microarrays (Affymetrix). Anti-CD25 treatment inhibited several genes typically expressed during T-cell activation including granzyme B, signalling lymphocyte activation molecule, family member 1 (SLAMF1), CD40-Ligand (CD40-L), IL-9 and interferon (IFN)-gamma. Interestingly, anti-CD25 mAb also blocked the expression of several genes important for susceptibility to apoptosis, such as death receptor 6 (DR6) or reversed IL-2-mediated repression of anti-apoptotic genes, such as Fas apoptotic inhibitory molecule 3 (FAIM3)/TOSO. Functional significance of DR6 and TOSO expression in IL-2-dependent T-cell activation was subsequently evaluated by RNA interference in AICD: While siRNA specifically directed against DR6 did not modulate FAS-L-mediated apoptosis induction in primary T cells, down-regulation of TOSO significantly increased susceptibility to apoptosis, emphasizing an important role for TOSO in IL-2-mediated AICD.
authors.affiliation: Laboratory for Functional Genomics and Transplantation Biology, Department of Pediatrics and Children's Cancer Research Center, Technische Universität München, 81664 München, Germany. somagene@lrz.tum.de
authors.forename: G H S
authors.initials: GH
authors.lastname: Richter
authors.forename: A
authors.initials: A
authors.lastname: Mollweide
authors.forename: K
authors.initials: K
authors.lastname: Hanewinkel
authors.forename: C
authors.initials: C
authors.lastname: Zobywalski
authors.forename: S
authors.initials: S
authors.lastname: Burdach
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000276:immunology*; D051017:Apoptosis Regulatory Proteins / Q000096:biosynthesis* / Q000235:genetics; D017252:CD3 Complex / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects / Q000276:immunology; D020869:Gene Expression Profiling; D020868:Gene Silencing / Q000276:immunology; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D053645:Interleukin-2 Receptor alpha Subunit / Q000037:antagonists & inhibitors* / Q000276:immunology; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D034741:RNA, Small Interfering / Q000276:immunology / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D017252:CD3 Complex; C112037:FCMR protein, human; D007376:Interleukin-2; D053645:Interleukin-2 Receptor alpha Subunit; D008565:Membrane Proteins; D034741:RNA, Small Interfering; D018124:Receptors, Tumor Necrosis Factor; C114109:TNFRSF21 protein, human