INTRA-PERITONEAL FREE ELASTASE IN CAPD PERITONITIS

Neutrophil (PMN) recruitment into the peritoneum during acute bacteria l peritonitis is an important part of the host defense barrier in CAPD patients. However, the subsequent phagocytosis of bacteria may also l ead to PMN degranulation and the release of lysosomal enzymes. We dete rmined the concentration of neutrophil elastase, both in complex with its natural inhibitor alpha1Pi (Ealpha1Pi), and in uncomplexed, free f orm, in infected and normal CAPD peritoneal fluid by ELISA. In additio n elastase activity was estimated in a casein degradation assay. Infec ted fluid contained a median (range) of 1.4 nm (0 to 9.2) free elastas e by ELISA and 1.2 nm (0 to 11.9) activity. There were strong correlat ions between the peritoneal leukocyte count and both immunoreactive el astase and activity (r = 0.816, P < 0.001, 0.687, P < 0.01, respective ly). In contrast, normal fluid contained 0.0 nm (0 to 0.32) immunoreac tive elastase (P < 0.01) and 0.0 nm (0 to 0.6) elastase activity (P < 0.001). Ealpha1Pi complexes were raised significantly during peritonit is at 6.2 nm (0 to 34.3) and were barely detectable in normal fluid 0. 0 nm (0 to 0.17; P < 0.005). The study shows that small but significan t quantities of uninhibited elastase can be detected in the peritoneal fluid of CAPD patients with acute bacterial peritonitis. This observa tion may have important implications for the pathogenesis of peritonea l membrane damage and the phlogistic response to infection.