Prospective comparison of blood and peritoneal lymphocytes from continuous ambulatory peritoneal dialysis patients

Although a few studies have analyzed the characteristics of peritoneal lymphocytes from continuous ambulatory peritoneal dialysis (CAPD) patients, there have been no definitive longitudinal investigations comparing peripheral blood lymphocytes (PBL) with peritoneal lymphocytes (PL) from these patients. Therefore, the purpose of this study was to prospectively compare the phenotypes of PBL and PL of CAPD patients and to determine if phenotypic changes occurred from the initiation of CAPD therapy over the subsequent 12 months. Patients were categorized into younger (< 60 years) or older (> 60 years) to determine if age-related factors contributed to differences in lymphocyte phenotypes. Blood and overnight peritoneal dialysate effluents (PDE) were obtained from 18 patients at the initiation of CAPD therapy and for 11 successive months. Fourteen lymphocyte subsets were quantitated using monoclonal antibodies and flow cytometry analysis. CAPD patients had significantly higher percentages of peripheral activated T (CD3⁺/HLA-DR⁺) cells and natural killer (CD57⁺) cells at the beginning of CAPD than normal controls. There were significantly greater percentages of B cells, activated T cells, and suppressor T (CD8⁺/CD11b⁺) cells and significantly fewer helper T (CD4⁺) cells in the PDE as compared with the patients' peripheral lymphocytes. No significant changes were observed over time in the phenotypes of PBL and only one PL phenotype showed significant changes with fluctuating levels of CD4⁺/CD45RA⁺ cells with continued peritoneal dialysis. In general, these findings suggest that although both PBL and PL activation is occurring in clinically uninfected patients, the characteristics of lymphocytes are stable over time.