Abstract:

Objective To study the expressions of Toll-like receptor 9 protein （TLR9） in peripheral B and T lymphocytes in newly diagnosed, untreated patients with systemic lupus erythematosus （SLE） and their relationship with clinical parameters. Methods Blood samples were obtained from 35 newly diagnosed, untreated patients with SLE and 16 healthy human controls. B, T lymphocytes and TLR9 protein were labeled with fluorescent antibodies, and the expressions of TLR9 protein were detected by flow cytometry in peripheral B and T lymphocytes. The relationship between TLR9 expression and clinical parameters was assessed. Results The proportions of B and T lymphocytes expressing TLR9 in newly diagnosed, untreated patients were （53.94 ± 17.95）% and （49.33 ± 23.30）%, respectively, compared to （29.40 ± 10.54）% and （29.18 ± 14.78）%, respectively, in healthy controls （t = 6.11，3.73, respectively, both P < 0.01）. Additionally, the proportion of B lymphocytes expressing TLR9 correlated negatively with SLE disease activity index （SLEDAI）（r = -0.39, P < 0.05）, but positively with the level of serum IgA antibody （r = 0.74, P < 0.01）. Conclusions The expression of TLR9 is elevated in peripheral T and B lymphocytes from patients with newly diagnosed, untreated SLE, and the proportion of TLR9-expressing B lymphocytes negatively correlates with SLEDAI, but positively correlates with the serum level of IgA antibody.