The expression of inflammatory cytokines in arthritic joints of mice with peptidoglycan–polysaccharide (PG-PS)-induced arthritis. Total RNA was extracted from ankle joints, reversely transcribed, amplified by PCR, and resolved on gel electrophoresis. The upper panel shows 24 cycles of amplification with tumor necrosis factor (TNF)-α specific primers, and the lower panel shows 22 cycles of amplification with glyceraldehyde-3-phosphate dehydrogenase (GAPDH)-specific primers. The first two lanes on the left represent DNA molecular weight markers. Lane (-) represents a negative control (RT-PCR amplification in the absence of RNA sample). Lanes N1 and N2 represent RT-PCR amplified RNA from nonarthritic joints of normal (i.e. not injected with PG-PS) wild-type and CD14 knockout animals, respectively. Lanes a–d represent RT-PCR amplified RNA from four different arthritic joints of PG-PS-injected wild-type animals. Lanes e–g represent RT-PCR amplified RNA from three arthritic joints of PG-PS injected CD14 knockout animals. Representative data from two independent experiments are shown.