The presence of lymphoid aggregates in rheumatoid arthritis (RA) synovia is associated with elevated total immunoglobulin message, but not protein. GAPDH-normalized message for IgM (a) and IgG1 (b) heavy constant region in cDNA from RA synovia with (Aggr, n = 8) or without (No aggr, n = 17) lymphoid aggregates. Serum-normalized levels of (c) total IgM and (d) total IgG in extracts from the same synovia as in (a) and (b). Tissues were obtained by arthroplasty or arthroscopic shaver biopsy, and cDNA was analyzed by quantitative real-time polymerase chain reaction (a, b). Extracts were analyzed by enzyme-linked immunosorbent assay for antibodies of interest and albumin (c, d). See Figure 1 legend for box plot definitions. Indicated P values were determined by Wilcoxon rank sum test. GAPDH, glyceraldehyde-3-phosphate dehydrogenase; REU, relative expression units; SSI, synovial/serum index.
Rosengren et al. Arthritis Research & Therapy 2008 10:R105 doi:10.1186/ar2497