OBJECTIVE: To investigate whether or not a change in dialysate interleukin-8 (IL-8) concentration precedes the onset of clinically overt peritonitis and is significant in the recruitment of granulocytes during continuous ambulatory peritoneal dialysis (CAPD)-related peritonitis. DESIGN: CAPD patients stored their overnight effluent at 4 degrees C, which was routinely thrown away after 2 days. If peritonitis developed, patients delivered their effluent of the preceding two nights and the peritonitis effluent for analysis. A control study was performed 1 to 3 months after recovery. Dialysate samples were analyzed for number of cells, differential cell count, IL-8 and elastase concentrations, and their neutrophil chemoattractive capacity. In addition, serum samples during peritonitis were analyzed for IL-8 concentrations. RESULTS: Ten peritonitis episodes in 7 patients were analyzed. Numbers of neutrophils and levels of dialysate IL-8 and elastase started to increase 4 to 12 hours before the first peritonitis effluent. The dialysate/serum IL-8 ratio was 423.5 during peritonitis and 7.0 in the postperitonitis controls. There was a significant correlation between the number of neutrophils and IL-8 concentration in the dialysate. The in vitro neutrophil chemotaxis was increased toward the peritonitis effluents, as compared to control effluents. Incubation of the peritonitis effluents with anti-IL-8 monoclonal antibody blocked the increase in neutrophil chemotaxis above control levels by an average of 26.7%. CONCLUSION: IL-8 is produced in the peritoneal cavity during CAPD treatment and may mediate part of the neutrophil recruitment and degranulation in the initial phase of a CAPD peritonitis.

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