Dialysate and serum concentrations of tumor necrosis factor-alpha (TNF-alpha), soluble TNF-receptor I (sTNFRI) and soluble TNF-receptor II (sTNFRII) were measured during stable and infectious CAPD to determine whether these mediators are released intraperitoneally or derived from the circulation. Dialysate/serum ratios were compared to those of various marker proteins for peritoneal transport and to interleukin-6 (IL-6), which is locally produced. Peritoneal immunoreactive TNF-alpha could be detected in 19 of 20 stable CAPD patients after a night dwell, but only occasionally and in lower concentrations during and after a standard four-hour peritoneal permeability test. Both sTNFRs highly exceeded TNF-alpha dialysate concentrations. In case of peritonitis a median 16-fold increase in dialysate TNF-alpha occurred on the first day, which declined towards control values during a longitudinal follow-up of eight consecutive days. sTNFRI and sTNFRII in dialysate increased three- to fourfold. Their peaks, however, appeared on the second peritonitis day. Bioactive TNF-alpha was only detected when immunoreactive levels exceeded 1000 pg/ml. Serum values of all variables were not altered during infection; sTNFRs exceeded TNF-alpha 300- to 400-fold. During stable CAPD indirect evidence was obtained for transperitoneal transport from plasma to dialysate of TNF-alpha (molecular wt 17 kD), sTNFRI (55 kD) and sTNFRII (75 kD). Dialysate/serum (D/S) ratios were higher, the lower the molecular weight; they were related to D/S ratios of those marker proteins with the nearest molecular weight; D/S ratios were unrelated to the intraperitoneally produced IL-6. Furthermore, the observed D/S ratios were as expected theoretically for their molecular weights.(ABSTRACT TRUNCATED AT 250 WORDS)

The local production of cancer antigen (CA) 125 in the peritoneal cavity of 14 continuous ambulatory peritoneal dialysis patients was studied. In addition, the relationship between the concentration of mesothelial cells and CA 125 in the peritoneal dialysate effluent was examined. The median results and ranges were as follows: plasma CA 125 14 U/mL (range 10 23), dialysate CA 125 18 U/mL (range 5.2 76), dialysate/plasma ratio 1. 9 (range 0.61 -5.4), and number of mesothelial cells 400/mL (range 10 5000). Peritoneal concentrations of mesothelial cellsand CA 125 were positively correlated (r = 0.50, p < 0.01). Using a monoclonal antibody, CA 125-positive cells were found in the cytospin preparations of the cells of dialysis effluents. All these CA 125 positive cells were also positive for cytokeratin used as a mesothelial cell marker. In vitro experiments using mesothelial cells in monolayers showed a linear increase in CA 125 concentration both in time and in relation to the number of mesothelial cells. From these experiments a production rate of 24 U/hour/1 06 cells could be calculated. It is therefore concluded that CA 125 is locally produced in the peritoneal cavity during CAPD and that the mesothelial cells are the major source of this CA 125.

Cytokines are pluripotent pleiotropic agents that have received widespread attention over the last few years. Not surprisingly, they have also been studied in the context of continuous ambulatory peritoneal dialysis. Cytokines play a central role in this treatment modality for uremic patients, because these inflammatory mediators act upon the biological dialysis membrane, i.e. the peritoneum, while simultaneously they participate in host defense mechansims. This review describes which cytokines are present in dialysate, whether there is support for intraperitoneal release, and under which circumstances. It focuses particularly on the relationship between cytokines in peritoneal effluent and peritoneal permeability to macromolecules. In addition, the presence of prostanoids in dialysate and their role in the local regulation of peritoneal permeability are discussed, because cyclooxygenase products are tightly linked to cytokine networks.

Objective To investigate whether dialysate concentrations of substances that are locally produced within the peritoneal cavity can be used to study the effects of inflammation on peritoneal tissue. Design We followed the appearance rates (AR) of concentrations of cancer antigen (CA) 125, phospholipids (PHL), hyaluronan (HA), and the procollagen peptides PICP (procollagen 1 C-terminal) and PIIINP (procollagen 3 N-terminal) in dialysate during peritonitis (8 consecutive days) and after recovery. Data were compared with the stable situation. Setting CAPD (continuous ambulatory peritoneal dialysis) unit in the Academic Medical Center in Amsterdam. Patients Twelve CAPD patients with a total of 16 episodes of peritonitis and 10 clinically stable CAPD patients were studied. Results All substances showed temporal increments in dialysate during peritonitis compared to control. No difference was found between the control day of peritonitis and the stable patients. Maximum AR were reached in the acute phase of peritonitis for CA 125, PHL, and HA and on day 4 for both PICP and P111NP. A second increment in CA125 occurred on days 4 to 6. These findings indicate acute damage to the mesothelium (CA 125) and other cells (PHL) by the infection. HA may reflect stromal changes. Subsequently, peritoneal healing (PICP, PIIINP) and remesothelialization (second peak CA125) are likely to occur. Conclusions Dialysate concentrations of these substances can be used as markers for the effects of peritonitis on the peritoneum of CAPD patients in vivo. The similarity between the marker concentrations in the effluent after recovery from peritonitis and those in stable CAPD patients implies that complete peritoneal healing is likely to occur after uncomplicated peritonitis.