RESUMO
We previously reported that 4C8 monoclonal antibody (mAb) provides a costimulatory signal to human CD4+ T cells and consequently induces regulatory T (Treg) cells, which are hypo-responsive and suppress the polyclonal response of bystander CD4+ cells in a contact-dependent manner. In this study, we identified the antigen of 4C8 mAb as CD52. Costimulation with Campath-1H, a humanized anti-CD52 mAb, also induced Treg cells. Anti-CD52-induced Treg cells suppressed the proliferation of both CD4+ and CD8+ T cells provided with polyclonal or allogeneic stimulation. When Treg cells were induced from Staphylococcal enterotoxin B (SEB) treated cells, they suppressed the response to SEB more efficiently than that to another superantigen, SEA. Furthermore, anti-CD52-induced Treg cells could be expanded by culture with IL-2 followed by CD52-costimulation, and co-injection of expanded Treg cells suppressed lethal xenogeneic graft versus host disease (GvHD) reactions in SCID mice caused by human peripheral blood mononuclear cells (PBMCs).
Assuntos
Antígenos CD/imunologia , Antígenos de Neoplasias/imunologia , Glicoproteínas/imunologia , Linfócitos T Reguladores/imunologia , Alemtuzumab , Animais , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais Humanizados , Anticorpos Antineoplásicos/imunologia , Antígenos CD/biossíntese , Antígeno CD52 , Linfócitos T CD8-Positivos/citologia , Linfócitos T CD8-Positivos/imunologia , Enterotoxinas/imunologia , Epitopos de Linfócito T/imunologia , Feminino , Fatores de Transcrição Forkhead/biossíntese , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/imunologia , Doença Enxerto-Hospedeiro/imunologia , Humanos , Interleucina-2/imunologia , Ativação Linfocitária/imunologia , Camundongos , Camundongos SCID , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Linfócitos T Reguladores/citologiaRESUMO
NKT cells represent a unique subset of immunoregulatory T cells that recognize glycolipid Ags presented by the MHC class I-like molecule CD1d. Because of their immunoregulatory properties, NKT cells are attractive targets for the development of immunotherapies. The prototypical NKT cell ligand alpha-galactosylceramide (alpha-GalCer), originally isolated from a marine sponge, has potent immunomodulatory activities in mice, demonstrating therapeutic efficacy against metastatic tumors, infections, and autoimmune diseases, but also has a number of adverse side effects. In vivo administration of alpha-GalCer to mice results in the rapid activation of NKT cells, which is characterized by cytokine secretion, surface receptor down-regulation, expansion, and secondary activation of a variety of innate and adaptive immune system cells. In this study, we have evaluated the in vivo immune response of mice to a set of structural analogues of alpha-GalCer. Our results show that, contrary to current thinking, beta-anomeric GalCer can induce CD1d-dependent biological activities in mice, albeit at lower potency than alpha-anomeric GalCer. In addition, we show that the response of NKT cells to distinct GalCer differs not only quantitatively, but also qualitatively. These findings indicate that NKT cells can fine-tune their immune responses to distinct glycolipid Ags in vivo, a property that may be exploited for the development of effective and safe NKT cell-based immunotherapies.
