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. Key Points • Primary Sjögren’s syndrome (pSS) is a chronic and systemic autoimmune disease. pSS patients had elevated blood levels of CD38 + HLA-DR + CD8 + T cells and IFN-γ. • The CD38 + HLA-DR + CD8 + T cells positively correlated with disease parameters and serum IFN-γ. • The salivary glands of pSS patients had appreciable CD8 + lymphocyte infiltration. CD8 + T cells may play crucial role in the pathogenesis of pSS.