MHC Class I-Restricted Determinants on the Glutamic Acid Decarboxylase 65 Molecule Induce Spontaneous CTL Activity

Abstract

CD4+ T cell responses to glutamic acid decarboxylase (GAD65) spontaneously arise in nonobese diabetic (NOD) mice before the onset of insulin-dependent diabetes mellitus (IDDM) and may be critical to the pathogenic process. However, since both CD4+ and CD8+ T cells are involved in autoimmune diabetes, we sought to determine whether GAD65-specific CD8+ T cells were also present in prediabetic NOD mice and contribute to IDDM. To refine the analysis, putative Kd-binding determinants that were proximal to previously described dominant Th determinants (206–220 and 524–543) were examined for their ability to elicit cytolytic activity in young NOD mice. Naive NOD spleen cells stimulated with GAD65 peptides 206–214 (p206) and 546–554 (p546) produced IFN-γ and showed Ag-specific CTL responses against targets pulsed with homologous peptide. Conversely, several GAD peptides distal to the Th determinants, and control Kd-binding peptides did not induce similar responses. Spontaneous CTL responses to p206 and p546 were mediated by CD8+ T cells that are capable of lysing GAD65-expressing target cells, and p546-specific T cells transferred insulitis to NOD.scid mice. Young NOD mice pretreated with p206 and p546 showed reduced CTL responses to homologous peptides and a delay in the onset of IDDM. Thus, MHC class I-restricted responses to GAD65 may provide an inflammatory focus for the generation of islet-specific pathogenesis and β cell destruction. This report reveals a potential therapeutic role for MHC class I-restricted peptides in treating autoimmune disease and revisits the notion that the CD4- and CD8-inducing determinants on some molecules may benefit from a proximal relationship.

MS and clinically isolated syndromes: Shared specificity but diverging clonal patterns of virus‐specific IgG antibodies produced in vivo and by CSF B cells in vitro

“…This is in line with previous findings in T1D showing that T cell epitopes to GAD65 localise to residues 481-495, 511-525 and 551-585 (Patel 1997;Nepom 2001). Furthermore, the C-terminal region is also targeted by CD8 + T cells and of interest, tolerance-inducing DNA coding for the Cterminal region, GAD 500-585 , has been shown to protect NOD mice from diabetes (Quinn 2001;Han 2005).…”

T-cell vaccination leads to suppression of intrapancreatic Th17 cells through Stat3-mediated RORγt inhibition in autoimmune diabetes

“…At 10 days later, immunized mice were sacrificed and SMCs were prepared from the spleens of GAD65 peptide p206-220-immunized mice and HEL peptide p11-25-immunized mice and plated out at 10 7 cells/well in 24-well culture plates in the presence of 20 µg/ml the peptide, respectively [51]. After 7 days of incubation, all cultures were re-stimulated with irradiated autologous SMC (3 000 rad, Co60) pulsed with the peptide, and supplemented with rIL-2 at 100 IU/ml after 48 h. After another 7 days, all cultures were examined for specific proliferation in response to the peptide using 3 H proliferation assays.…”

Early Autoimmune Destruction of Islet Grafts Is Associated with a Restricted Repertoire of IGRP-Specific CD8+ T Cells in Diabetic Nonobese Diabetic Mice

“…This included IGRP 206 -214 and the corresponding NRP-V7 mimotope, in addition to InsB [15][16][17][18][19][20][21][22][23] , and DMK 138 -146 . H2K d -restricted peptides derived from ProIns B25-C34 (37) and GAD65 (GAD65 546 -554 ) (38) were also tested. Pooled pancreatic islets from groups of four 20-wk-old NOD female mice were cultured for 3 days in IL-2-containing medium.…”