The Relationship Between B-cell Activating Factor And Systemic Lupus Erythematosus

To investigate the relationship between B-cell activating factor (BAFF) and systemic lupus erythematosus (SLE), and to explore the potential effect of cytokines on promoter activity of BAFF gene, and to find a new approach to the treatment of SLE, we set up a real-time quantitative reverse transcription (RT)-PCR method to examine the specific expression of BAFF gene. This assay was based on fluorescent TaqMan methodology when using prokaryotic expressing vector pMD18-T- BAFF as a standard plasmid. Anti-Human BAFF monoclonal antibody and polyclonal antibody were used as antibodies to detect serum BAFF levels by ELISA. Serum samples from patients with SLE were assayed for BAFF levels, quantitative immunolobulins (IgG, IgA, IgM), and anti-double-stranded DNA(anti-dsDNA) antibody levels. The specific gene expression of BAFF in those patients was also examined with the real-time RT-PCR assay. More importantly, five chimeric genes were constructed with various lengths of sequences between 1020 bp upstream of the start of transcription site of human BAFF gene. The sequences were fused to chloramphenicol acetyltransferase (CAT) reporter gene, and these recombinant plasmids were transiently transfected to HL-60 cells. Cytokines (IFN-γ, IL-10, IL-4 and rhBAFF) treatment was continued for another 24 hours after transfection. The putative promoters activities were tested and compared by CAT measurement in those transfected cells.