The frequency of CD4+ and CD8+ circulating T stem cell memory in type 1 diabetes

The frequencies and functions of T stem cell memory (TSCM) subsets vary in autoimmune diseases. We evaluated the frequencies of CD4⁺ and CD8⁺ TSCM subsets as well as their PD-1 expression levels in patients with T1D.

Blood samples were collected from new case (NC) (n = 15), and long-term (LT) (n = 15) groups and healthy controls (n = 15). Five subsets of T cells including TCM(CD4⁺ /CD8⁺ CCR7⁺ CD45RO⁺ CD95⁺ ), TCM^hi (CD4⁺ /CD8⁺ CCR7⁺ CD45RO^hi CD95⁺ ), TEM(CD4⁺ /CD8⁺ CCR7^- CD45RO⁺ CD95⁺ ), TSCM(CD4⁺ /CD8⁺ CCR7⁺ CD45RO^- CD95⁺ ), and T naive (CD4⁺ /CD8⁺ CCR7⁺ CD45RO^- CD95^- ) were detected by flow-cytometry.

The frequency of CD4⁺ TSCM was higher in NC patients than LT patients and controls (p < .0001 and p = .0086, respectively). A higher percentage of the CD8⁺ T naive cells was shown in NC patients as compared with LT and healthy individuals (p = .0003 and p = .0002, respectively). An increased level of PD-1 expression was observed on the CD4⁺ TCM and TCM^hi cells in LT patients as compared with healthy controls (p = .0037 and p = .0145, respectively). Also, the higher PD-1 expression was observed on the CD8⁺ TCM and TCM^hi in NC and LT patients as compared with controls (p = .0068 and p < .0001; p = .0012 and p = .0012, respectively).

Considering TSCMs' capacities to generate all memory and effector T cells, our results may suggest a potential association between the increased frequencies of TSCMs and T1D progression.