BLyS protein and BLyS isoform mRNA levels in normal individuals, and RA, and SLE patients. (a) Plasma from normal individuals (Nl), and RA and SLE patients were assayed for BLyS levels by ELISA. Each symbol indicates an individual subject. The composite results are plotted as box plots. The lines inside the boxes indicate the medians, the outer borders of the boxes indicate the 25th and 75th percentiles, and the bars extending from the boxes indicate the 10th and 90th percentiles. The thin solid line across the plot indicates the lower limit of detection in the BLyS assay (0.3 ng/ml). (b,c) RNA was extracted from peripheral blood buffy coats from the same individuals. Amounts of full-length BLyS, ΔBLyS, and actin mRNA were quantified by real-time RT-PCR, and results are shown as ratios of full-length BLyS mRNA (b) and ΔBLyS mRNA (c) to actin mRNA. BLyS, B lymphocyte stimulator; ELISA, enzyme-linked immunosorbent assay; RA, rheumatoid arthritis; RT-PCR, reverse transcription polymerase chain reaction; SLE, systemic lupus erythematosus.