Alterations of CD8(+) T cells in the blood and salivary glands of patients with primary Sjögren’s syndrome

OBJECTIVE: To identify the alterations of CD8(+) T cells in blood and labial salivary glands (LSGs) of patients with Primary Sjögren’s syndrome (pSS). METHODS: Blood samples from 24 pSS patients were assayed for CD38(+) HLA-DR(+) CD8(+) (activated CD8(+), aCD8(+)) T cells and serum IFN-γ and TNF-α, using flow cytometry and ELISA respectively, and compared with samples from 27 healthy controls. Immunohistochemistry was used to count CD8(+) T cells in LSG tissues of 24 pSS patients and of 6 control patients with normal pathology. RESULTS: pSS patients had more aCD8(+) T cells than aCD4(+) T cells (medians 33.13% vs. 9.43%, p < 0.0001), and had an increased level of aCD8(+) T cells (medians 33.13% vs. 16.48%, p < 0.0001) and serum IFN-γ (medians 1026 pg/mL vs. 0.00 pg/mL, p < 0.0001) compared to the healthy controls. The levels of aCD8(+) T cells and IFN-γ were both significant positively correlated with European League Against Rheumatism Sjögren’s Syndrome Disease Activity Index, IgG, anti-nuclear antibodies, rheumatoid factor. The LSGs focus score (FS) ≥1 group had more CD8(+) T cell counts than 0≤ FS <1 group and control group (medians 256/mm(2) vs. 126/mm(2) and 256/mm(2) vs. 64/mm(2) respectively, both p < 0.05). CONCLUSION: The aCD8(+) T cells and IFN-γ are positively correlated with each other, and predominantly elevated in the blood of pSS patients. In the LSG tissues of pSS, CD8(+) T cell counts increase with severity of the lesions. CD8(+) T cells may play crucial role in the pathogenesis of pSS. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10067-022-06491-7.