Altered frequencies of memory B cells in new-onset systemic lupus erythematosus patients.

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease, characterized by B cell hyperactivity and pathogenic autoantibodies formation. The objective of this study is to evaluate the distribution of B cell subsets in patients with SLE. We included patients with SLE followed in First Affiliated Hospital of Xi'an JiaoTong University, Xi'an, China. Flow cytometry was used to measure frequencies of B cell subsets, including memory B cells, switched memory B cells, non-switched memory B cells, double-negative memory B cells, and naïve B cells in 130 patients with SLE and 55 healthy controls. The different distributions of B cell subsets were further evaluated by their associations with disease activity and clinical manifestation. SLE patients showed significant alteration of B cell subsets, including lower frequency of non-switched memory B cells and higher double-negative memory B cells. The frequencies of B cell subsets also varied between new-onset SLE patients and chronic SLE patients. Frequencies of total memory B cells, switched memory B cells, and non-switched memory B cells were lower in new-onset SLE patients and frequency of naïve B cells was higher compared with healthy controls. Chronic SLE patients showed increased switched memory B cells and double-negative memory B cells. In addition, switched memory B cells and double-negative B cells were higher in patients with lupus nephritis (LN) regardless of disease activity. Our findings suggested that abnormalities of the B cell subsets homeostasis might contribute to the pathogenesis of SLE.