Characterization of 5C11-positive activated interferon-producing cells in patients with systemic lupus erythematosus.

OBJECTIVE: 5C11 antibody is a novel monoclonal antibody against human BST2 and can be used to detect activation of interferon-producing cells (IPCs). Activated IPCs, which produce large amounts of interferon-α (IFNα), are considered to play an important role in the pathogenesis of systemic lupus erythematosus (SLE). We investigated the characterization of 5C11-positive cells in patients with SLE. METHODS: The proportions of 5C11-positive cells among blood dendritic cell antigen 2 (BDCA-2)-, CD3-, CD19- and CD14-positive cells in peripheral blood from SLE patients (SLE-PBMCs) and healthy controls (control-PBMCs) were analyzed by flow cytometry. The effect of 5C11 antibody on IFNα production from SLE-PBMCs under stimulation with cytosine-phosphate-guanosine (CpG2216, bacterial oligonucleotide motif) was also examined by enzyme-linked immunosorbent assay (ELISA). RESULTS: The proportions of 5C11-positive cells among BDCA-2-, CD3- and CD19-, but not CD14-positive cells in SLE-PBMCs were significantly increased compared to those in control-PBMCs (p < 0.0001, all). Especially, the number of 5C11-positive cells among BDCA-2-positive cells was significantly increased in SLE-PBMCs by about six-fold compared to that in control-PBMCs (p < 0.0001). 5C11 antibody inhibited IFNα production by SLE-PBMCs induced by CpG and the inhibition rates was 27% (p < 0.001). CONCLUSION: SLE patients had a significantly higher proportion of 5C11-positive cells among CD3 and CD19 cells, and especially BDCA-2 positive cells. The ability of 5C11 antibody to inhibit IFNα production from SLE-PBMCs warrants further investigation for its possible clinical application for the treatment of SLE.