[Show abstract][Hide abstract] ABSTRACT: Peptides, either as altered peptide ligands, competitors, or vaccines, offer an outstanding potential for regulating immune responses because of their exquisite specificity. However, a major problem associated with peptide therapies is that they are poorly taken up by APCs. Because of poor bioavailability, high concentrations and repeated treatments are required for peptide therapies in vivo. To circumvent this problem, we tested whether covalently coupling a peptide T cell determinant, OVA(323-339), to transferrin (Tf) enhances APC uptake and presentation as monitored by Th cell activation. Functional analysis of the Tf-peptide conjugates revealed that the conjugates were presented 10,000- and 100-fold more effectively by B cells than intact Ag and free peptide, respectively. Furthermore, we demonstrate that the Tf-peptide conjugates are taken up by B cells through a receptor-mediated process and subsequently delivered to the lysosomal compartment. Using an adoptive transfer assay, we show that that the Tf-peptide complexes are 100-fold more effective in vivo than the free peptide in activating CD4(+) T cells by following an early activation marker, CD69. Our results demonstrate that coupling peptides to Tf enhances peptide presentation, thereby making it possible to take full advantage of peptide-specific therapies in modulating T cell responses.
Full-text · Article · Oct 2002 · The Journal of Immunology
[Show abstract][Hide abstract] ABSTRACT: Activation of helperT cell has been implicated in a number of autoimmune diseases including rheumatoid arthritis. The underlying mechanism that initiates and promotes disease progression remains unclear, but it is apparent that helper T cells and autoantigens play prominent roles. Identification of the autoantigens has proven to be extremely difficult, and therefore strategies for promoting tolerance induction remain limited. Since autoimmune diseases are closely associated with specific major histocompatibility complex class II molecules such as HLA-DR4, the use of competitor peptides is an alternative strategy. A limitation of competitor peptides, however, is that they are ineffective in vivo. In the studies presented here, we demonstrate that coupling competitor peptides to a cell-surface receptor ligand, transferrin, enhances their ability to block helper T cell responses using the DO11.10 transgenic mouse as our model system.
Full-text · Article · Feb 2002 · Immunologic Research