Down-regulation of CD43 molecule expression on the surface of intraperitoneal neutrophils in CAPD peritonitis

Recent reports on the detection of intraperitoneal free elastase in CAPD peritonitis may have important implications concerning the pathogenesis of peritoneal membrane damage. In order to assess the release of proteases from neutrophils infiltrating the peritoneal cavity in CAPD peritonitis, we investigated the regulation of CD43, LAM-1 and Mac-1 expression on the neutrophil plasma membrane by FACS analysis. Down-regulation of CD43 and LAM-1, and up-regulation of Mac-1 were found on neutrophils obtained from dialysates after a 1-hour dwell-time. Up-regulation of Mac-1 continued to increase until a 4-hour dwell-time. Immunoblot analysis for neutrophil lysate from dialysate showed the presence of asialo form CD43 molecules and their fragments, which may have been produced by cleavage of CD43 molecules at extracellular sites. These results suggest that the intraperitoneal neutrophils in CAPD peritonitis are continuously activated during dwell-time, and that proteases may be released from neutrophils in dialysate even after a short dwell-time, in spite of the low pH and high lactate concentration.