Peripheral T cell clones from NOD mice specific for GAD65 peptides: lack of islet responsiveness or diabetogenicity

The non-obese diabetic (NOD) mouse develops diabetes as a result of spontaneous T cell mediated destruction of the insulin-producing beta-cells. Tolerization to glutamic acid decarboxylase (GAD65) has been reported to inhibit spontaneous T cell proliferative responses to GAD65 and GAD65 peptides and prevent insulitis and diabetes in NOD mice. To evaluate the role of T cells responsive to GAD65 in induction of diabetes in NOD mice we generated T cell clones from spleen cells of three prediabetic NOD mice using the reported immunodominant human GAD65 peptides nos. 17, 34 and 35, which are spontaneously recognized by NOD spleen cells. The ten T cell clones established from two female and one male NOD mice recognized either the GAD65 peptide no. 35 which has an identical amino acid sequence in mice and humans or recognized the human GAD65 peptide no. 17 which is different in two amino acids from murine GAD65 peptide no. 17. None of the clones exhibited responses to islet cells, and GAD65 peptide no. 17 responsive clones did not cross react with the murine GAD65 peptide no. 17. All clones were CD4 positive and expressed the alpha/beta T cell receptor, but differed in their V beta usage. Analysis of in vitro production of IFN gamma, IL-2 and IL-4 demonstrated a TH1 and TH0 like functional subset of the individual clones. In vivo, neither the autoreactive T cell clones specific for GAD65 peptide no. 35 nor the xenoreactive clones specific for GAD65 peptide no. 17 were able to accelerate diabetes in young NOD mice or transfer diabetes into NODscid mice.