Abstract:

Objective To explore the differentiation of B lymphocytes and expression of B7-related protein-1 （B7RP-1） on B lymphocytes in patients with systemic lupus erythematosus （SLE）. Methods Three-color immunofluorescent staining and flow cytometric assay were used to analyze the frequency of three types of B lymphocytes, i.e., plasma cells, memory B lyphocytes and naive B lymphocytes, as well as the expression of B7RP-1 on these cells in peripheral blood from 23 patients with SLE and 16 normal human controls. Clinical data of these patients with SLE were collected, and SLE disease activity index （SLEDAI） was also evaluated. The relationship was assessed between the expression of B7RP-1 and SLEDAI. Results The frequency of plasma cells was highest in patients with active SLE, followed by patients with inactive SLE and normal human controls （P < 0.01）. A significant decrease was observed in the frequency of memory B lymphocytes in patients with active SLE compared with normal controls （P < 0.01）, but no significant difference was found between patients with inactive SLE and those with active SLE （P > 0.05）. Regarding the frequency of naive B lymphocytes, there was no significant difference among the three groups. Increased frequency of plasma cells was also noted in patients with lupus nephritis （LN） compared with those without LN ［（6.15 ± 3.12）% vs （3.31 ± 1.41）%, P < 0.05］, but no significant difference was found with regard to the frequency of memory or naive B lymphocytes between these two groups. The expression rate of B7RP-1 was significantly lower on total lymphocytes from patients with SLE than from normal human controls （46.51% vs 63.75%, P < 0.05）, which was the case with B7RP-1 on plasma cells, memory B lyphocytes and naive B lymphocytes （all P < 0.01）, whereas no significant difference was found between patients with inactive SLE and active SLE or between patients with and without LN. In addition, no correlation was found between the expression of B7RP-1 and SLEDAI （r = 0.035, P > 0.05）. Conclusions In peripheral blood of patients with SLE, the frequency of plasma cells is increased, while the expression of B7RP-1 on lymphocytes is decreased, which may be relevant to the pathogenesis of SLE.