Unlike PD-L1, PD-1 Is Downregulated on Partial Immune Cells in Type 2 Diabetes

INTRODUCTION: Type 2 diabetes is a worldwide disease which is associated with chronic, low-grade inflammation. The PD-1/PD-L1 pathway has been reported to be a negative regulatory element in immune homeostasis and to be involved in many diseases. MATERIALS AND METHODS: Peripheral blood mononuclear cells (PBMCs) were obtained from type 2 diabetes patients (n = 23) and healthy donors (n = 20). The PD-L1 and PD-1 expressions on corresponding immune cells were evaluated by flow cytometry. RESULTS: The PD-L1 expression on corresponding immune cells has no significant difference between these two groups. We showed the downregulated PD-1 expression in type 2 diabetes patients. The correlation analysis indicated that the PD-1 on NK cells has a positive correlation with insulin and diabetes duration. And an inverse correlation has been shown between the PD-1 expression on monocytes and BMI (body mass index). CONCLUSIONS: The results in this article suggest that PD-1, unlike PD-L1, might participate in the progression of type 2 diabetes. This investigation will provide evidence for the potential immune therapy for T2D.