Peritoneal fluid markers of mesothelial cells and function

Dialysate Cancer Antigen 125 Concentration as Marker of Peritoneal Membrane Status in Patients Treated with Chronic Peritoneal Dialysis

Objective

This study reviews publications on the history of cancer antigen 125 (CA125), the background of its use as a marker of mesothelial cell mass, determination in peritoneal effluent, and its practical use in both the follow-up of peritoneal dialysis (PD) patients and as a marker of in vivo biocompatibility of dialysis solutions.

Design

Review article.

Results

CA125 is a high molecular weight glycoprotein. Previous studies in ascites suggested its release by mesothelial cells. In vitro studies with cultured mesothelial cells showed constitutive production, the majority of which was dependent on mesothelial cell mass. Serum CA125 is normal in PD patients, but its concentration in peritoneal dialysate suggests local release, probably from mesothelial cells. Effluent CA125 can be considered a marker of mesothelial cell mass in stable PD patients, but large amounts are found during peritonitis, due probably to necrosis of mesothelial cells. The majority of studies found no relationship between dialysate CA125 and peritoneal transport parameters. Some cross-sectional studies reported a relationship with duration of PD, but others were unable to confirm this, due probably to the large interindividual variability. Longitudinal follow-up has shown a decrease in dialysate CA125, indicating loss of mesothelial cell mass. Application of theoretically morebiocompatible PD solutions causes an increase in dialysate CA125.

Conclusions

Dialysate CA125 is a mesothelial cell mass marker. The concentration of CA125 should be determined after a standardized dwell. A single low value is not informative. A decrease with time on PD suggests loss of mesothelial cell mass. Dialysate CA125 is a marker of in vivo biocompatibility of (new) dialysis solutions. More research is necessary on the best methodology for measuring low concentrations and establishing normal values and a significant change.

Mesothelium and Malignant Mesothelioma

The mesothelium is an epithelial structure derived from the embryonic mesoderm. It plays an important role in the development of a number of different organs, including the heart, lungs, and intestines. In this publication, we discuss aspects of the development of the mesothelium, where mesothelial structures can be found, and review molecular and cellular characteristics associated with the mesothelium. Furthermore, we discuss the involvement of the mesothelium in a number of disease conditions, in particular in the pathogenesis of mesotheliomas with an emphasis on malignant pleural mesothelioma (MPM)—a primary cancer developing in the pleural cavity.

Monitoring of the peritoneal membrane

Background. Indirect methods can be used to provide valuable information about peritoneal structure and function for the indirect analysis of peritoneal membrane. Methods. The focus of this paper will be on the commonly available tools for this purpose. First, the value and clinical relevance of CA125 as a marker of mesothelial cell mass in peritoneal effluent will be evaluated. Thereafter, monitoring the peritoneal membrane by using its properties to transport solutes and water will be discussed. Results. The data obtained can be useful for tailoring dialysis adequacy, analysis of clinical problems such as ultrafiltration failure or to predict the development of peritoneal sclerosis.

Dialysate CA125 levels in children on continuous peritoneal dialysis

This prospective study was conducted to assess dialysate cancer antigen 125 (dCA125) levels in pediatric peritoneal dialysis (PD) patients and to investigate whether it exhibits any alterations during or after recovery from peritonitis, and also to analyze the relationships between dCA125 and age, duration of PD treatment, peritonitis incidence, time passed since the last episode of peritonitis, PD prescription parameters, and peritoneal transport parameters. Forty-seven standardized 4-h peritoneal equilibration tests (PET) were performed in 38 children (mean age 11.6+/-4.7 years) on PD (duration 20.9+/-14.3 months). Thirty-two of the patients were in stable condition at the time of PET (stable group). Six patients were included in the study only during a peritonitis episode, and two of the stable patients were reevaluated during a peritonitis episode afterwards (peritonitis group). Seven out of a total of eight patients with acute peritonitis were reexamined after recovery (recovery group). CA125 levels were measured in 188 samples at 0-, 1-, 2-, and 4-h dwells. Peritoneal appearance rates (AR) were calculated. Mean dCA125 (4 h) and AR CA125 values were 5.6+/-5.3 U/ml [median 4.15 U/ml/4 h (range 0.5-25.9)] and 50.1+/-45.6 U/min/1.73 m2[median 37.91 U/ml/1.73 m2 (range 3.61-223.39)]. AR CA125 levels did not correlate with age, PD duration, peritonitis incidence, time passed since the last peritonitis episode, exchange volume used per m2 per day, or peritoneal transport properties in the stable patients' group. Although stable patients using hypertonic PD solutions (n=16) had slightly lower AR CA125 levels (p=0.04), multivariate analysis showed no influence of hypertonic dextrose solutions on mesothelial CA125 secretion (p=0.4). During acute peritonitis, CA125 concentrations showed a reversible threefold increase [AR CA125: stable 37.9 vs. peritonitis 101.2 U/ml/1.73 m2 (p=0.001)]. No difference could be found between the stable group and the recovery group. We conclude that changes in the peritoneal mesothelial cell mass cannot be assessed by determining CA125 in a cross-sectional way and that longitudinal determinations could be more valuable in the follow-up of patients.