Anti-CD19 Monoclonal antibody, clone K4-230 [PerCP-eFluor® 710]

Background At present, anti-CD20 monoclonal antibody treatments targeting systemic lupus erythematosus (SLE) are complex, variable, and often have disappointing outcomes. High levels of programmed cell death-1 (PD-1) and its ligands (PD-L1, PD-L2) or CD80/CD86 on B cell surfaces are markers of increased B cell activity. However, their expression levels on CD19(+)CD20(+/-)B cells and their clinical significance for SLE dynamics have not been carefully investigated. Methods Flow cytometry was used to detect the expression levels of PD-1, PD-L1, PD-L2, CD80, and CD86 on CD19(+)CD20(+/-)B cells in peripheral blood from SLE patients and healthy controls (HCs). The amount of anti-dsDNA and immunoglobin G (IgG) secreted by CD19(+)CD20(+/-)B cells was measured by enzyme-linked immunosorbent assay. Results CD19(+)CD20(-)B cell frequency was significantly higher in SLE patients than in HCs (P < 0.001), and was positively correlated with disease activity. In SLE patients, frequencies of PD-1, PD-L1, PD-L2, and CD86 on CD19(+)CD20(-)B cells were significantly higher than CD19(+)CD20(+)B cells (P <= 0.002) and were significantly correlated with individual laboratory and clinically based parameters (P < 0.05). In vitro tests, we found that the levels of anti-dsDNA and IgG secreted by CD19(+)CD20(-)B cells from patients with SLE were significantly higher than the HC group (P < 0.05). Conclusions We found abnormal frequency of CD19(+)CD20(-)B cells and increased expression of surface markers on these cells from SLE patients. And the CD19(+)CD20(-)B cells had the ability to proliferate and secrete anti-dsDNA and IgG. Additionally, our results suggested that CD19(+)CD20(-)B cells from SLE patients may be the activated B cells and caused poor efficacy of rituximab.

Interleukin (IL)-10-producing B cells are recently known for their regulatory function in several disorders. However, the possible role of these cells remains unclear in recurrent pregnancy loss (RPL) pathogenesis. Total B cells from 24 RPL patients with cellular immune abnormalities, as well as that of 25 normal pregnant women were cultured and stimulated by Toll Like Receptor (TLR) agonists (CpG oligodeoxynucleotides (ODN) and imiquimod). Then, the frequency of IL-10(+) CD19(+ )B cells was found out using flow cytometry. Enzyme-linked immunosorbent assay (ELISA) was used to assess the levels of IL-10 in supernatant medium and serum of stimulated B cells, as well as those of several serum autoantibodies. Real-Time PCR method was carried out for determining the IL-10 expression level and specific genes transcripts. RPL patients indicated a lower proportion of IL-10(+) CD19(+) B cells, and reduced levels of IL-10 in both serum and supernatant of the culture medium of the stimulated B cells. According to the results, total IgG levels was greater in serum of RPL patients in comparison with healthy pregnant women. Similarly, the percentage of these cells was negatively correlated with serum total IgG levels and the number of miscarriages. The expression levels of the mRNA of programmed death-ligand 1 (PD-L1) and IL-10 were lower in RPL patients, while those of x binding protein 1 (XBP-1), interferon regulatory factor 4 (IRF4), and B lymphocyte-induced maturation protein 1 (BLIMP1) were significantly increased. These observations indicated that the reduction in the population of peripheral blood IL-10-synthesizing B cells may prompt RPL pathogenesis, suggesting suppressive effects of these cells on autoantibody production and successful pregnancy outcomes.