Diabetes, Vol 48, Issue 11 2157-2165, Copyright © 1999 by American Diabetes Association
Peptides derived from murine insulin are diabetogenic in both rats and mice, but the disease-inducing epitopes are different: evidence against a common environmental cross-reactivity in the pathogenicity of type 1 diabetes
VL Heath, P Hutchings, DJ Fowell, A Cooke and DW Mason
Medical Research Council Cellular Immunology Unit, Sir William Dunn School of Pathology, Oxford, UK. heath@dnax.org
Two rodent models of autoimmune type 1 diabetes have been used to
investigate the role of insulin as an autoantigen in this disease. In
lymphopoenia-induced diabetes in the PVG.RT1u rat, neonatal tolerization
with insulin B-chain peptides, but not A-chain peptides, conferred
significant protection from disease. After rechallenge of adult rats,
neonatally B-chain-tolerized animals showed diminished B-chain-specific
T-cell proliferation, interleukin (IL)-2 production, and interferon-gamma
(IFN-gamma) production, as compared with control animals. The epitope
recognized by the PVG.RT1u rat was mapped to residues 1-18 of the B-chain;
T-cell lines specific for this epitope were generated, and these conferred
diabetes upon adoptive transfer to irradiated syngeneic recipients. In
adult nonobese diabetic (NOD) mice, subcutaneous immunization with B-chain
peptide 9-23 emulsified in incomplete Freund's adjuvant (IFA) was also
potent at preventing onset of diabetes. In contrast to PVG.RT1u rats, NOD
mice recognized an epitope within residues 10-29 of the insulin B-chain.
The data implicate insulin as a target autoantigen in type 1 diabetes but
do not support a role for molecular mimicry to insulin in the pathogenesis
of this disease.