Detection of carboxypeptidase H specific T cells in peripheral blood of latent autoimmune diabetic patients with carboxypeptidase antibody positivity by ELISPOT assay / 中南大学学报(医学版)

ABSTRACT

Objective To explore the characteristics of T cell immunity in peripheral blood of patients with carboxypeptidase - H antibody (CPH-Ab). Methods Forty-two latent autoimmune diabetes in adults (LADA) patients with CPH-Ab~+ alone, 20 Type 2 diabetes mellitus patients (T2DM), and 22 healthy controls were selected and their peripheral blood mononuclear cells were isolated. Human recombinant carboxypeptidase (CPH) protein was expressed and further used as a stimulant in Enzyme-linked immunospot (ELISPOT) assay to detect IFN-γ-Th1 and IL-4-Th2 cells in the 3 groups. Th1/Th2 ratios were also calculated. CPH-Ab and glutamic acid decarboxylase antibody (GAD-Ab) were determined by radioligand assay. Results Compared with healthy controls and T2DM, IFN-γ-Th1 and IL-4-Th2 numbers did not increase significantly in CPH-Ab~+ group, nor did the Th1/Th2 ratios (P ＞0. 05). We further divided the CPH-Ab~+ patients into a short duration group (n = 22) and a long duration subgroup (n = 20) according to the duration of 3 years. CPH-IL-4-T in the short duration subgroup was significantly higher than that in T2DM and healthy controls (1. 8 vs. 0.2 and 0.3, both P ＜ 0. 05) and we did not find any factor that was significantly correlated with the IL-4 spots number. There were not any significant differences in T cell responses to phaseolus vulgaris agglutinin (PHA) among all groups (P＞0.05). Conclusion CPH does not directly involve in the cellular pathological mechanism of LADA. Anti-CPH immunity may be associated with more slowly aggressive beta cell autoimmunity.