To elucidate the pathogenetic mechanism of renal parenchymal injury in autosomal dominant polycystic kidney disease (ADPKD) patients, typically characterized by renal cystic changes paralleled by interstitial inflammation and gradual fibrotic changes, the role of selected inflammatory mediators was evaluated in a group of ADPKD patients with normal glomerular filtration rate. The plasma concentrations of IL-6, IL-8, ICAM-1 and VCAM-1 (which may reflect systemic response to inflammation/infection) were increased in the ADPKD patient group. Coupled with decreased urinary excretion of the IL-1 receptor antagonist (which exerts an anti-inflammatory role), these results suggest that even in overt infection free status, the proinflammatory system is more activated and anti-inflammatory defence system weakened in ADPKD subjects. Our data support the current view that cytokines are candidate contributors to pathogenesis of ADPKD.