T-cell promiscuity in autoimmune diabetes.
OBJECTIVE
It is well established that the primary mediators of beta-cell destruction in type 1 diabetes are T-cells. Nevertheless, the molecular basis for recognition of beta-cell-specific epitopes by pathogenic T-cells remains ill defined; we seek to further explore this issue.


METHODS
To determine the properties of beta-cell-specific T-cell receptors (TCRs), we characterized the fine specificity, functional and relative binding avidity/affinity, and diabetogenicity of a panel of GAD65-specific CD4(+) T-cell clones established from unimmunized 4- and 14-week-old NOD female mice.


RESULTS
The majority of GAD65-specific CD4(+) T-cells isolated from 4- and 14-week-old NOD female mice were specific for peptides spanning amino acids 217-236 (p217) and 290-309 (p290). Surprisingly, 31% of the T-cell clones prepared from 14-week-old but not younger NOD mice were stimulated with both p217 and p290. These promiscuous T-cell clones recognized the two epitopes when naturally processed and presented, and this dual specificity was mediated by a single TCR. Furthermore, promiscuous T-cell clones demonstrated increased functional avidity and relative TCR binding affinity, which correlated with enhanced islet infiltration on adoptive transfer compared with that of monospecific T-cell clones.


CONCLUSIONS
These results indicate that promiscuous recognition contributes to the development of GAD65-specific CD4(+) T-cell clones in NOD mice. Furthermore, these findings suggest that T-cell promiscuity reflects a novel form of T-cell avidity maturation.
Li
Li
L
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Wang
Bo
B
Frelinger
Jeffrey A
JA
Tisch
Roland
R
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D049109:Cell Proliferation; D016207:Cytokines / Q000378:metabolism; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D005968:Glutamate Decarboxylase / Q000276:immunology; D051379:Mice; D016688:Mice, Inbred NOD; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics / Q000276:immunology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020349:Surface Plasmon Resonance; D037182:T-Cell Antigen Receptor Specificity / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism
D016207:Cytokines; D000939:Epitopes; D016693:Receptors, Antigen, T-Cell, alpha-beta; D005968:Glutamate Decarboxylase; C401141:glutamate decarboxylase 2