Monoclonal antibody therapy directed at the alpha chain (TAC/CD25) of the high affinity IL-2 receptor (IL-2R) is a growing therapy in transplantation and autoimmune disease. However, the mechanisms by which this therapy may limit immune responses have not been fully elucidated. Using a humanized anti-TAC antibody in vitro, we investigated the role of IL-2R blockade in the regulation of Thl immune responses. Our preliminary data indicate HAT inhibits production of the Thl effector cytokine, IFN-y, and the central regulatory Thl cytokine, IL-12, from activated peripheral blood mononuclear cell (PBMC) cultures. We hypothesize CD40 ligand (CD40L)/CD40 interactions play a major role in HAT-mediated inhibition of IL-12- dependent Thl responses and show CD40L expression on activated T cells is biphasic, with HAT inhibiting late phase CD40L. In SA#1, we will extend this studies to determine whether differential regulation of CD40L on naive and memory T cells by CD28 costimulation and/or IL-2R signaling accounts for biphasic expression. We will also determine the role of IL-2R signaling in regulating IL-12R expression and IL-12 responsiveness in T cells, since IL-12 cannot restore IFN-gamma in the presence of HAT. In SA#2, we will focus on the molecular mechanisms by which IL-2R blockade and/or CD28 costimulation regulates CD40L gene expression. Using a 1.3Kb CD40L promoter reporter construct and transiently transfecting a Thl cell clone, we will test putative Stat5 binding elements to determine whether IL-2R blockade regulates CD40L expression at these sites. In SA#3, we hypothesize that HAT directly inhibits IFN-gamma production from T cells in an IL-12-independent, cell cycle-dependent mechanism. To test this, we will assess the effects of HAT on cell cycle progression, using carboxyfluorescin diacetate succinimidyl ester (CFSE)-Iabeling and co-staining for IFN-y in activated T cells subjected to cell cycle arrest at various stages. The PI, Dr. John McDyer is a junior faculty member and committed to a career in academic medicine and understanding the mechanisms through which anti-TAC .regulates human immune responses; this knowledge will improve our understanding of the role of IL-2R blockade in human T cell responses and differentiation and may expand the role for HAT antibody therapy in the treatment of immune-mediated diseases. This K08 will provide the foundation for a research career dedicated to translational studies in immunology.
| Shah, P D; West, E E; Whitlock, A B et al. (2009) CD154 deficiency uncouples allograft CD8+ T-cell effector function from proliferation and inhibits murine airway obliteration. Am J Transplant 9:2697-706 |
| Pipeling, Matthew R; West, Erin E; Osborne, Christine M et al. (2008) Differential CMV-specific CD8+ effector T cell responses in the lung allograft predominate over the blood during human primary infection. J Immunol 181:546-56 |
| McDyer, John F (2007) Human and murine obliterative bronchiolitis in transplant. Proc Am Thorac Soc 4:37-43 |
| Shlobin, Oksana A; West, Erin E; Lechtzin, Noah et al. (2006) Persistent cytomegalovirus-specific memory responses in the lung allograft and blood following primary infection in lung transplant recipients. J Immunol 176:2625-34 |
| West, Erin E; Lavoie, Tera L; Orens, Jonathan B et al. (2006) Pluripotent allospecific CD8+ effector T cells traffic to lung in murine obliterative airway disease. Am J Respir Cell Mol Biol 34:108-18 |
