Peritonitis in continuous ambulatory peritoneal dialysis: cytokines in peritoneal fluid and blood

Cytokines are soluble mediators of the immune system that regulate the response to antigens and microorganisms. In patients on continuous ambulatory peritoneal dialysis (CAPD) who have peritonitis, an inflammatory process exists that must be understood if susceptibility to, and the mechanisms of, complications such as fibrosis and others are to be understood. To that end, we studied 9 CAPD patients with peritonitis. The case series was conducted in Popayán, Colombia, at the RTS Cauca dialysis unit and the University of Cauca hospital, a tertiary health care facility. Peritonitis was diagnosed by standard clinical and laboratory criteria. Using flow cytometry, we measured the percentage production of intracellular cytokines [interleukin-1 alpha (IL-1 alpha), IL-6, IL-12, tumor necrosis factor alpha (TNF alpha), IL-4, and interferon-gamma (IFN-gamma) in T lymphocytes from blood and peritoneal fluid. Among the studied patients, all (100%) produced high levels of IL-1, IL-6, TNF alpha, IL-12, and IL-4 in both fluids (blood: 89% +/- 63% of cells; peritoneal fluid: 81.6% +/- 10.1% of cells). In blood, 25% of patients produced IFN-gamma (mean: 15.7% of cells), showing that 75% of patients had the TH2 pattern, and 25% were close to TH0. In peritoneal fluid, 34% of patients produced IFN-gamma spontaneously (mean: 24.5% of cells), indicating that 66% of patients were TH2, and 34% were close to TH0. After stimulation, expression of cytokines, including IFN-gamma (39% of T cells), was increased, and high production of IL-4 indicated that 25% of patients were TH2, and 75% were TH0. In peritoneal fluid, production of cytokines, including IFN-gamma, was increased, with high production of IL-4, indicating switching from TH2 (34% of patients) to TH0 (66% of patients). Of the studied patients, 35% had a CD4:CD8 ratio < 1.1 in blood, and also produced IL-12 (94.5% of cells) and IFN-gamma (30% of cells), as compared with patients in whom the CD4:CD8 ratio was > 1.2. Patients on CAPD who have peritonitis produce large amounts of pro-inflammatory and TH2 cytokines. More IFN-gamma is produced in peritoneal fluid than in blood, which suggests more inflammation. Immunodeviation TH2 is seen in blood and peritoneal fluid of CAPD patients with peritonitis. Patients with a CD4:CD8 ratio < 1.1 produce more IFN-gamma and IL-12, and are more able to switch from TH2 to TH0.