Relationship between interleukin-8 and neutrophil adhesion molecules in rheumatoid arthritis

To evaluate the role of interleukin-8 (IL-8) on the activation of neutrophils in rheumatoid arthritis (RA), we measured IL-8 and the adhesion molecules, L-selectin (CD62L), CD11b and CD18, on neutrophils in paired peripheral blood and synovial fluid of RA patients, Synovial fluid IL-8 levels were significantly increased compared to peripheral blood. L-selectin was split off and CD11b and CD18 were upregulated on neutrophils in the synovial fluid. A positive correlation occurred between the IL-8 concentration and CD18 or CD11b densities on neutrophils in the synovial fluid (r=0.75, P<0.005 and r=0.60, P<0.05, respectively). Peripheral blood neutrophils of the patients were desensitised with IL-8 in vivo, as shown by the significantly lower L-selectin shedding after in vitro IL-8 stimulation: 1.6 times decrease for patients vs 3.2 for controls (P<0.05). In conclusion, these results add further evidence for the role of IL-8 in the activation of neutrophils in RA.