[Abnormal T cell autoimmunity against GAD65 in LADA patients]

To explore the T cell-mediated immunopathogenesis of latent autoimmune diabetes in adults (LADA).

Seventeen LADA patients, 28 T2DM (type 2 diabetes mellitus) patients and 16 healthy controls were recruited. GAD-Ab, IA-2Ab and CPH-Ab were determined by radioligand assays. Human peripheral blood mononuclear cells were isolated by Ficoll-Hypaque density gradients. And the spot numbers of IFN-γ-secreting T cells (IFN-γ-Th1) and IL-4-secreting T cells (IL-4-Th2) were detected by enzyme linked immunospot (ELISPOT) assay. One spot-forming represented a GAD(65)-reactive IFN-γ/IL-4-secreting T cell. The ratio (balance) of Th1/Th2 was defined as IFN-γ-Th1/IL-4-Th2.

(1) The spot numbers of IFN-γ-Th1 (median) were 4.0, 2.0 and 1.0 in LADA, T2DM and control while those of IL-4-Th2 2.0, 3.3 and 1.0 and Th1/Th2 3.0, 0.4 and 0.3 respectively; (2) As compared to T2DM or control group, significant increases of Th1 (P < 0.01) and Th1/Th2(P < 0.05) were observed in LADA group. But the spot numbers of Th2 showed no significant differences among three groups (P > 0.05). And there were no differences of Th1 and Th1/Th2 between T2DM and control group (P > 0.05); (3) No significant difference of Th1 or Th2 was observed for phytohemagglutinin (PHA) stimulation in three groups (P > 0.05).

Significantly enhanced IFN-γ-Th1 cells and a shift of Th1/Th2 towards Th1 are present in LADA patients. They may contribute to the T-cell mediated immunopathogenesis of LADA.