RESUMO
BACKGROUND: Activated T cells play a key role in allograft rejection. T cell activation requires signaling via the T cell receptor as well as costimulatory signals. Inducible costimulatory molecule (ICOS), with its ligand B7RP-1, is a recently discovered costimulatory molecule of the CD28 family. The role of this signaling pathway during the early phases of kidney allograft rejection is not clear so far. METHODS: Kidneys were orthotopically transplanted from BALB/c to C57BL/6 mice. Animals were assigned to five experimental groups: blocking anti-ICOS monoclonal antibody, ICOS fusion protein, anti-B7RP1 monoclonal antibody, B7RP-1 fusion protein, and control immunoglobulin G. RESULTS: Survival was significantly reduced in animals treated with ICOS monoclonal antibody (mAb) and B7RP-1 Fc as compared with controls. These animals had also a lower number of apoptotic graft infiltrating T cells, whereas the expression of intracellular interferon-gamma in CD3CD4 T cells was increased. Animals treated with ICOS Fc and B7RP-1 mAb had similar survival and numbers of apoptotic T cells as compared with controls. CONCLUSIONS: In summary, the blockade of ICOS with ICOS mAb or B7RP-1 Fc reduced the amount of apoptosis of infiltrating lymphocytes and resulted in continuous inflammatory processes with progressive tissue damage and graft failure.
Assuntos
Antígenos de Diferenciação de Linfócitos T/uso terapêutico , Antígeno B7-1/uso terapêutico , Rejeição de Enxerto/tratamento farmacológico , Transplante de Rim/imunologia , Animais , Anticorpos Monoclonais , Antígenos de Diferenciação de Linfócitos T/imunologia , Apoptose , Antígeno B7-1/imunologia , Complexo CD3/biossíntese , Complexo CD3/genética , Imunoadesinas CD4/biossíntese , Imunoadesinas CD4/genética , Modelos Animais de Doenças , Citometria de Fluxo , Expressão Gênica , Rejeição de Enxerto/imunologia , Rejeição de Enxerto/metabolismo , Sobrevivência de Enxerto , Marcação In Situ das Extremidades Cortadas , Ligante Coestimulador de Linfócitos T Induzíveis , Proteína Coestimuladora de Linfócitos T Induzíveis , Líquido Intracelular/metabolismo , Transplante de Rim/patologia , Ligantes , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , RNA Mensageiro/genética , Linfócitos T/imunologia , Linfócitos T/patologiaRESUMO
We describe here the bioengineering of a bivalent IFN-gamma-RFc immunoadhesin consisting of the extracellular domain of the human IFN-gamma receptor alpha chain (IFN-gamma-R) fused to a human IgG1 Fc region (encoding hinge, CH2 and CH3 domain) that was efficiently expressed as a covalently linked homodimer in insect cells and purified in a one-step purification procedure. The IFN-gamma-RFc fusion protein exerted a 3-fold higher ligand binding affinity in binding competition studies in vitro compared with the monovalent extracellular IFN-gamma-R domain. In addition, the in vitro antagonistic activity of IFN-gamma-RFc, as determined by inhibition of IFN-gamma-induced virus protection and HLA-DR expression, was more than 30-fold higher in comparison with the monovalent soluble receptor. The described IFN-gamma-R immunoadhesin is a potential therapeutic reagent to interfere with the disease-promoting activities of IFN-gamma in several autoimmune diseases.
