Analysis of mRNA levels of selected genes in synovial tissue from rheumatoid arthritis (RA) as compared to that from osteoarthritis (OA) patients by semiquantitative reverse transcription polymerase chain reaction (RT-PCR). Bars represent means ± SD of signal intensities after amplification of samples (see Materials and methods). The data from one representative experiment with one determination per patient sample are shown. Differences between RA and OA sample groups were statistically evaluated using the Student's t-test (*P < 0.05, **P < 0.01, ***P < 0.001). (a) RT-PCR analysis of 10 cDNA samples derived from patients with RA and of 10 cDNA samples from patients with OA. cDNA samples were adjusted to equal glyceraldehyde-3-phosphate dehydrogenase (G3PDH) levels, performed by competitive PCR using an internal standard (see Materials and methods). Numbered lanes correspond to individual patients within Table 1. (b) Quantitation of the expression of Cys–X–Cys receptor (CXCR)1, CXCR2, CXCR3, T-cell receptor (TCR)-ζ, Cys–X–Cys ligand (CXCL)9, and CXCL10 mRNAs in RA and OA synovial tissues. (c) CXCR/TCR-ζ mRNA ratios in RA versus OA synovial tissues.