Dialysate interleukin-15 concentration and ultrafiltration capacity in patients undergoing peritoneal dialysis

Our aim in the present study was to simultaneously determine, in peritoneal dialysis (PD) patients, interleukin-15 (IL-15) concentrations in serum and dialysate, peritoneal transport parameters, and ultrafiltration (UF). The study was performed in 42 patients who had been treated with PD for 24.5 +/- 20.1 months. Concentration of IL-15 was measured (ELISA: IBL, Hamburg, Germany) during a peritoneal equilibration test. Of 42 patients, 69% had serum IL-15 concentrations above normal values (< 13.0 pg.mL). The mean dialysate-to-plasma ratio (D/P) for IL-15 exceeded 1. We observed a negative relationship between dialysate IL-15 and effluent volume. Patients with UF < or = 200 mL or < 100 mL had higher dialysate IL-15 concentration, higher D/P for IL-15, higher mass transfer area coefficient (KBD) for creatinine, and higher dialysate creatinine concentration than patients with more UF. The KBD for creatinine correlated negatively with dialysate effluent volume. We conclude that, in PD patients, elevated serum and dialysate IL-15 concentrations confirm the existence of systemic and local inflammation; the source of IL-15 in dialysate is not only serum, but also local generation in the peritoneum; and dialysate IL-15 concentration may be a marker of UF capacity.