Circulating СD8+ T Cells Subsets in Primary Sjögren’s Syndrome

Currently, multiple studies have indicated that CD8+ T lymphocytes play a role in causing damage to the exocrine glands through acinar injury in Primary Sjogren’s syndrome (pSS). The aim of this research was to assess the imbalance of subsets within CD8+ cells in peripheral blood. We examined blood samples from 34 patients with pSS and 34 healthy individuals as controls. We used flow cytometry to enumerate CD8+ T cell maturation stages using as markers CD62L, CD28, CD27, CD4, CD8, CD3, CD45RA, and CD45. For immunophenotyping of ‘polarized’ CD8+ T cell subsets we used the following monoclonal antibodies:CXCR5, CCR6,CXCR3 and CCR4. The findings revealed that both the relative and absolute numbers of 'naïve' CD8+ T cells were higher in pSS patients compared to the healthy volunteers. Conversely, the proportions of effector memory CD8+ T cells were notably lower. Furthermore, our data suggested that among patients with pSS, the levels of cytotoxic Tc1 CD8+ T cells were reduced, while the frequencies of regulatory cytokine-producing Tc2 and Tc17 CD8+ T cells were significantly elevated. Simultaneously, the Tc1 cell subsets displayed a negative correlation with immunoglobulin G, Rheumatoid factor, the Schirmer test, and unstimulated saliva flow. On the other hand, the Tc2 cell subsets exhibited a positive correlation with these parameters. In summary, our study indicated that immune dysfunction within CD8+ T cells, including alterations in Tc1 cells, plays a significant role in the development of pSS.