The interaction of organism, phagocyte and mesothelial cell

Cancer Antigen 1251S Locally Produced in the Peritoneal Cavity during Continuous Ambulatory Peritoneal Dialysis

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.

Interleukin-1β Stimulates Glucose Uptake of Human Peritoneal Mesothelial CellsIn Vitro

To investigate whether the glucose uptake (GU) of human peritoneal mesothelial cells (HPMC) is mediated by glucose transporters and whether this uptake is influenced by interleukin 1–β (IL-1β), we measured 2-deoxy-(3H)-GU of HPMC in vitro, after exposing the cells for different times (two and 12 hours) to increasing concentrations (0.1, 1.0, and 2.0 ng/mL) of IL-1 β. To exclude a noncarrier-mediated transport, GU was also tested in the presence of cytochalasin B. All experiments were performed in triplicate in the cells of two donors.

Cytochalasin B inhibits GU of HPMC almost completely. GU of HPMC is not stimulated by insulin. GU is stimulated by IL-1 β in a dose-dependent manner.

These data indicate a GU of HPMC, which is mediated by a glucose transporter and stimulated by IL-1 β. The increased uptake of glucose from the dialysate In patients with peritonitis may be mediated by a (cytokineinduced) increased activity of HPMC glucose transporters.

Peritoneal dialysis research in the UK: the Cardiff contribution

The hallmark of the Cardiff contribution to our understanding of peritoneal dialysis over the past quarter century has been their translational approach to research, combining strong basic science with intelligent clinical questions. Their themes have included describing the biology of the dialyzed membrane; elucidation of several overlapping mechanisms of bioincompatibility, resulting in the development and testing of more biocompatible solutions; and describing the morphological changes with time on treatment and the membrane's response to infection. This has extended to investigation of the mechanisms controlling initiation and resolution by the innate immune system, relevant to both long-term membrane injury and a wider understanding of immunobiology. More than any other group, they have held the torch for basic science in peritoneal dialysis research.

Host defences in continuous ambulatory peritoneal dialysis and the genesis of peritonitis

Continuous ambulatory peritoneal dialysis (CAPD) has come to be extensively used for the treatment of end-stage renal failure in children, and especially infants, such that now more than half of children on dialysis worldwide receive treatment by this means. Peritonitis, however, is commoner in children than in adults receiving treatment, and is a major source of morbidity and treatment failure in children started on CAPD. Only recently has the immunology of the normal peritoneum been studied extensively, with the need to assess the impact of the installation of large volumes of fluid into the peritoneal sac during dialysis. The main phagocytic defences of the peritoneum depend upon a unique set of macrophages which are present free in the peritoneal fluid but also in the submesothelium and in perivascular collections together with B lymphocytes in the submesothelial area. Both the number of macrophages per unit volume and the concentration of opsonic proteins, such as IgG, complement and fibronectin, are reduced to between only 1% and 5% when dialysis fluid is continuously present in the peritoneal sac. In addition, the fluids used for CAPD are toxic to both macrophages and to mesothelial cells. Thus minor degrees of contamination frequently lead to peritonitis and in addition the majority of patients have catheters inserted in their peritoneum which become colonised with organisms capable of producing exopolysaccharide (slime), which promotes adhesion of the organism to the plastic and protects them against phagocytic attack and the penetration of antibiotics. Thus the peritoneum is in a state of continual inflammation, as well as being a markedly more vulnerable site than the normal peritoneum to the entry of organisms. Whether clinical peritonitis appears in this state of chronic contamination probably depends on perturbation in the balance between host defences and the organism. Whilst Staphylococcus epidermidis is the commonest cause of peritonitis, Staphylococcus aureus and Gram-negative organisms are much more serious and more frequently lead either to temporary catheter removal or discontinuation of dialysis altogether. This review describes the peritoneal defences in relation to the genesis of peritonitis.