HUMAN PERITONEAL B-1 CELLS AND THE INFLUENCE OF CONTINUOUS AMBULATORYPERITONEAL-DIALYSIS ON PERITONEAL AND PERIPHERAL-BLOOD MONONUCLEAR CELL (PBMC) COMPOSITION AND IMMUNOGLOBULIN LEVELS

In mice, peritoneal B cells are composed of a unique B-1 cell populati on which can repopulate the intestinal lamina propria with IgA-produci ng cells, as well as contribute to the majority of serum IgM. In this study, peritoneal lymphocytes from patients starting continuous ambula tory peritoneal dialysis (CAPD) and from women undergoing bilateral tu bal ligation (BTL) were analysed for the presence of a B-1 cell popula tion as well as the expression of potential homing receptors. Up to 63 % of the peritoneal B cells express surface antigen CD5, and most peri toneal lymphocytes express the mucosal homing receptors, alpha 4 beta 7 and alpha E beta 7. When analysing serial samples collected from pat ients from the beginning of dialysis to 1 year, no marked changes were observed in serum or salivary immunoglobulin levels, although the per itoneal lymphocyte population was reduced by 50%. These data suggest t hat the phenotype of human peritoneal B-1 cells is similar to that of mice, but the contributions to the immune system may differ.