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 vs. 126/mm and 256/mm vs. 64/mm 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.