A GMCSF-neuroantigen (NAg) fusion protein targets NAg to dendritic cells (DC) and is an effective therapy for experimental autoimmune encephalomyelitis (EAE) (50.10)

Abstract

Abstract The GM-CSF and M-CSF cytokines were tested as domains in cytokine-NAg fusion proteins to assess targeting of NAg to different APC subsets. Fusion proteins were designed with a cytokine N-terminal domain and the encephalitogenic peptide 69-88 of guinea pig myelin basic protein (MBP) as the C-terminal domain. Studies measuring T-cell activation in vitro, prevention of EAE, and treatment of EAE showed that GMCSF-NAg was the most potent fusion protein, represented by the following rank order of activity (GMCSF-NAg > MCSF-NAg > GP69-88). GMCSF-NAg was 1000-fold more potent than GP69-88 in stimulating MBP-specific T-cell proliferation. The mechanism by which GMCSF-NAg promoted T-cell activation involved cytokine receptor-mediated uptake of NAg by antigen presenting cells (APC), because free GM-CSF inhibited the GMCSF-NAg potentiated response. GMCSF-NAg potently targeted NAg to dendritic cells and macrophages in vitro, but not to B or T cell APC. Covalent linkage between GM-CSF and NAg was required for enhanced potency of GMCSF-NAg in vitro and for the prevention and treatment of EAE in vivo. In conclusion, GMCSF-NAg potently targeted self-antigen to myeloid APC subsets and caused profound antigen-specific tolerance in EAE. This study was supported by research grants from the National Multiple Sclerosis Society and the Brody Brothers Endowment Fund.