The inability to process a self-peptide allows autoreactive T cells to escape tolerance.
It is now clear that antigen presenting cells (APCs) do not present all the possible peptides of self-proteins to the immune system. When then, is the fate of T cells specific for those self-peptides that escape processing? In this study, the COOH-terminal peptide (residues 81-104) of self cytochrome c (cyt c) elicited strong autoimmune T cells, as well as autoantibodies specific for this immunogen. These T cells did not respond to stimulation with the whole self cyt c molecule, demonstrating that APCs cannot process and present the self 81-104 peptide. Whereas mice were unresponsive to immunization with the whole mouse cyt c molecule, the mouse 81-104 fragment together with the whole self-molecule induced and amplified the autoimmune T cell response to sites within the 1-80 peptide. T cells that never contact the relevant self-peptide are functionally ignorant. They do not become tolerized or deleted, nor do they normally participate in immune responses to the native whole self-protein, since APCs cannot present the 81-104 peptide.
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06510.
M J
MJ
Mamula
D000818:Animals; D001324:Autoantigens / Q000276:immunology*; D003574:Cytochrome c Group / Q000276:immunology; D007108:Immune Tolerance; D008213:Lymphocyte Activation; D051379:Mice; D008815:Mice, Inbred Strains; D013601:T-Lymphocytes / Q000276:immunology*
D001324:Autoantigens; D003574:Cytochrome c Group