Identification of MHC class II-restricted peptide ligands, including a glutamic acid decarboxylase 65 sequence, that stimulate diabetogenic T cells from transgenic BDC2.5 nonobese diabetic mice.
Nonobese diabetic (NOD) mice spontaneously develop insulitis and destruction of pancreatic islet beta cells similar to type 1 diabetes mellitis in humans. Insulitis also occurs in the BDC2.5 TCR transgenic line of NOD mice that express the rearranged TCR alpha- and beta-chain genes of a diabetogenic NOD CD4 T cell clone. When activated with syngeneic islet cells in culture, BDC2.5 T cells adoptively transfer disease to NOD recipients, but the identity of the islet cell Ag responsible for pathogenicity is not known. To characterize the autoantigen(s) involved, BDC2.5 T cells were used to screen a combinatorial peptide library arranged in a positional scanning format. We identified more than 100 decapeptides that stimulate these T cells at nanomolar concentrations; they are then capable of transferring disease to NOD-scid mice. Surprisingly, some of the peptides include sequences similar (8 of 10 residues) to those found within the 528-539 fragment of glutamic acid decarboxylase 65. Although this 12-mer glutamic acid decarboxylase 65 fragment is only slightly stimulatory for BDC2.5 T cells (EC(50) > 100 microM), a larger 16-mer fragment, 526-541, shows activity in the low micromolar range (EC(50) = 2.3 microM). Finally, T cells from prediabetic NOD mice respond spontaneously to these peptide analogs in culture; this finding validates them as being related to a critical autoantigen involved in the etiology of spontaneous diabetes and indicates that their further characterization is important for a better understanding of underlying disease mechanisms.
Judkowski
V
V
Torrey Pines Institute for Molecular Studies, San Diego, CA 92121, USA.
Pinilla
C
C
Schroder
K
K
Tucker
L
L
Sarvetnick
N
N
Wilson
D B
DB
D019264:Adoptive Transfer; D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D003922:Diabetes Mellitus, Type 1 / Q000201:enzymology* / Q000209:etiology / Q000276:immunology*; D005260:Female; D005968:Glutamate Decarboxylase / Q000276:immunology* / Q000302:isolation & purification / Q000378:metabolism; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007527:Isoenzymes / Q000276:immunology* / Q000302:isolation & purification / Q000378:metabolism; D008024:Ligands; D008213:Lymphocyte Activation / Q000276:immunology*; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology* / Q000302:isolation & purification / Q000378:metabolism; D019151:Peptide Library; D011236:Prediabetic State / Q000276:immunology; D017386:Sequence Homology, Amino Acid; D013601:T-Lymphocytes / Q000201:enzymology* / Q000276:immunology* / Q000637:transplantation
D000949:Histocompatibility Antigens Class II; D007527:Isoenzymes; D008024:Ligands; D010446:Peptide Fragments; D019151:Peptide Library; D005968:Glutamate Decarboxylase; C401141:glutamate decarboxylase 2