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[Report] Pathogenic CD4 T cells in type 1 diabetes recognize epitopes formed by peptide fusion

ScienceNOW - Fetched: February 11th, 2016, 3:00pm UTC

T cell–mediated destruction of insulin-producing β cells in the pancreas causes type 1 diabetes (T1D). CD4 T cell responses play a central role in β cell destruction, but the identity of the epitopes recognized by pathogenic CD4 T cells remains unknown. We found that diabetes-inducing CD4 T cell clones isolated from nonobese diabetic mice recognize epitopes formed by covalent cross-linking of proinsulin peptides to other peptides present in β cell secretory granules. These hybrid insulin peptides (HIPs) are antigenic for CD4 T cells and can be detected by mass spectrometry in β cells. CD4 T cells from the residual pancreatic islets of two organ donors who had T1D also recognize HIPs. Autoreactive T cells targeting hybrid peptides may explain how immune tolerance is broken in T1D. Authors: Thomas Delong, Timothy A. Wiles, Rocky L. Baker, Brenda Bradley, Gene Barbour, Richard Reisdorph, Michael Armstrong, Roger L. Powell, Nichole Reisdorph, Nitesh Kumar, Colleen M. Elso, Megan DeNicola, Rita Bottino, Alvin C. Powers, David M. Harlan, Sally C. Kent, Stuart I. Mannering, Kathryn Haskins

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