Elevated Expression of Immunoreceptor Tyrosine-Based Inhibitory Motif (TIGIT) on T Lymphocytes is Correlated with Disease Activity in Rheumatoid Arthritis

BACKGROUND It is well known that lymphocytes play an important role in rheumatoid arthritis (RA). T cell immunoreceptors with immunoglobulin (Ig) and immunoreceptor tyrosine-based inhibitory motif (TIGIT) have immunosuppressive co-stimulatory molecules that mediate inhibitory effects, but their roles in RA are poorly understood. MATERIAL AND METHODS Were recruited 76 patients with RA and 33 healthy controls (HC). Clinical manifestations, laboratory measurements, physical examination, and medical history of RA patients were recorded. The expression of TIGIT on CD3+ T lymphocytes, B lymphocytes, monocytes, neutrophils, CD3+CD4+ T lymphocytes, and CD3+CD8+ T lymphocytes was determined using flow cytometry. The expression of TIGIT on T lymphocytes in patients with RA was further analyzed to investigate its correlations with markers of autoimmune response, inflammation, and disease activity in RA. RESULTS Compared with HC, the expression levels of TIGIT on CD3+CD4+ T lymphocytes and CD3+CD8+ T lymphocytes were significantly increased in patients with RA (P < 0.01). The frequency of TIGIT-expressing CD3+CD4+ T lymphocytes was positively correlated with RF, increased ACPA, ESR, and CRP levels. The frequency of TIGIT-expressing CD3+CD8+ T lymphocytes was positively correlated with RF and ESR levels. Furthermore, the expression level of TIGIT on CD3+CD4+ T lymphocytes was positively correlated with the DAS28 score in RA. CONCLUSIONS The expression levels of TIGIT on T lymphocytes were elevated and correlated with disease activity in RA.