Activation of insulin-reactive CD8 T-cells for development of autoimmune diabetes.
OBJECTIVE
We have previously reported a highly diabetogenic CD8 T-cell clone, G9C8, in the nonobese diabetic (NOD) mouse, specific to low-avidity insulin peptide B15-23, and cells responsive to this antigen are among the earliest islet infiltrates. We aimed to study the selection, activation, and development of the diabetogenic capacity of these insulin-reactive T-cells.


METHODS
We generated a T-cell receptor (TCR) transgenic mouse expressing the cloned TCR Valpha18/Vbeta6 receptor of the G9C8 insulin-reactive CD8 T-cell clone. The mice were crossed to TCRCalpha-/- mice so that the majority of the T-cells expressed the clonotypic TCR, and the phenotype and function of the cells was investigated.


RESULTS
There was good selection of CD8 T-cells with a predominance of CD8 single-positive thymocytes, in spite of thymic insulin expression. Peripheral lymph node T-cells had a naïve phenotype (CD44lo, CD62Lhi) and proliferated to insulin B15-23 peptide and to insulin. These cells produced interferon-gamma and tumor necrosis factor-alpha in response to insulin peptide and were cytotoxic to insulin peptide-coated targets. In vivo, the TCR transgenic mice developed insulitis but not spontaneous diabetes. However, the mice developed diabetes on immunization, and the activated transgenic T-cells were able to transfer diabetes to immunodeficient NOD.scid mice.


CONCLUSIONS
Autoimmune CD8 T-cells responding to a low-affinity insulin B-chain peptide escape from thymic negative selection and require activation in vivo to cause diabetes.
Wong
F Susan
FS
Department of Cellular and Molecular Medicine, University of Bristol, Bristol, UK. susan.wong@bristol.ac.uk
Siew
Lai Khai
LK
Scott
Gwen
G
Thomas
Ian J
IJ
Chapman
Stephen
S
Viret
Christophe
C
Wen
Li
L
D019264:Adoptive Transfer / Q000379:methods; D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D002470:Cell Survival; D003433:Crosses, Genetic; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology*; D005434:Flow Cytometry; D015789:HLA-A2 Antigen / Q000235:genetics; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D016688:Mice, Inbred NOD; D008822:Mice, Transgenic; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics; D013154:Spleen / Q000276:immunology
D015789:HLA-A2 Antigen; D007328:Insulin; D016693:Receptors, Antigen, T-Cell, alpha-beta