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

Abstract

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/mm2 vs. 126/mm2 and 256/mm2 vs. 64/mm2 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.