Microarray analysis of chemokine receptor gene expression in synovial fluid polymorphonuclear neutrophils. (a) RNA of synovial fluid polymorphonuclear neutrophils (SF PMN) from nine patients with rheumatoid arthritis (RA) was analyzed for chemokine receptor expression. Data obtained by Gene Pix™ Analysis Software were normalized, transformed and denoted as x-fold regulation versus expression of blood PMN from healthy donors. Bars represent median expression between nine RNA samples. Genes with median expression ratios less than -1 or more than +1 were significantly regulated. (b) Total RNA from SF PMN from RA patients nos 1, 2, 7 and 8 and from blood PMN from healthy donor no. 2 was amplified by semiquantitative RT-PCR with primers for CCRL2, CXCR4 and actin and subjected to agarose gel electrophoresis. PCR was repeated twice.