CD25 monoclonal antibody binding to the α‐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)‐γ. 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.
The IL2R is a heterotrimeric receptor consisting of the alpha-chain (CD25) and the two signal transducing beta-, gamma-chains. CD25 monoclonal antibody (e.g. daclizumab) binding to the α-chain, blocks high affinity IL2 binding thereby preventing complete T cell activation. This opportunity to hinder T cell triggering is of ample importance in transplantation medicine and the treatment of autoimmune disease; e.g. for the prevention of an acute graft versus host reaction during allogeneic hematopoietic cell transplantation. However, gene-targeting experiments revealed, that CD25 has an important role in mediating activation induced cell death (AICD) thereby maintaining T cell homeostasis. Thus, CD25 antibodies may not only block T cell activation but may also prevent AICD attributing a dual function to IL2, which has been described by the term AICD paradoxon. The molecular mechanisms of AICD remain to be elucidated. In this study, the modulation of the genomic expression profile of human peripheral blood mononuclear cells (PBMC) with therapeutic concentrations of CD25 mAb was investigated with the aim to identify genes that are involved in T cell activation or in AICD. PBMC were stimulated with OKT3 together with recombinant IL2 in the absence or presence of 30 microgram/ml Daclizumab. Cells were incubated for 16 hrs, RNA extracted and subjected to microarray analysis on U133A gene chips (Affymetrix). Gene chip profile revealed up-regulation of 60 genes and down regulation of 36 genes respectively, by Daclizumab. Anti-CD25 treatment inhibitied cytokine genes typically expressed during T cell activation including CD40L, IL9, TNF-alpha and IFN-gamma as previously shown (e.g. Burdach et al., JCI). Surprisingly, daclizumab also blocked expression of several genes important for susceptibility to apoptosis, such as DR6. In addition, daclizumab reversed IL2-mediated repression of anti-apoptotic genes, such as TOSO. Microarray analysis of these apoptosis related genes was confirmed by RT-PCR and functional assays. In conclusion, CD25-mediated induction of pro-apoptotic as well as repression of anti-apoptotic gene clusters should be considered for future drug development of CD25-antibodies in the clinical arena: these apoptosis related gene products may represent new pharmacologic targets in hematopoietic cell transplantation as well as in the treatment of autoimmune diseases.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.