ANTIGEN-PRESENTING CAPACITY OF MACROPHAGES AND DENDRITIC CELLS IN THEPERITONEAL-CAVITY OF PATIENTS TREATED WITH PERITONEAL-DIALYSIS

In this study the antigen-presenting capacity of human peritoneal cell s and the influence of continuous ambulant peritoneal dialysis (CAPD) were studied. On average 6% of the peritoneal cells were dendritic cel ls (DC), with no difference between CAPD and control peritoneal cells. DC were enriched by selecting for non-adherent, Fc receptor-negative, low density cells. A typical spot-like CD68 positivity was seen in DC , in contrast to the pancytoplasmic staining pattern in macrophages. P eritoneal DC morphologically and functionally showed features of cells belonging to the DC lineage. Peritoneal DC were superior antigen-pres enting cells for both allo-antigen, and Candida albicans antigen or pu rified protein derivative. CAPD peritoneal macrophages were two- to th ree-fold better stimulator cells for allogeneic T cells compared with control macrophages. The level of integrins/adhesins or MHC class I or II, as measured semi-quantitatively on the FACS, could not account fo r this phenomenon. In addition, a double chamber system showed that di alysate-activated macrophages produced.soluble factors that could enha nce DC-induced allogeneic T cell proliferation. In conclusion, human p eritoneal cells contain a relatively high percentage of classical DC. CAPD treatment does not impair the antigen-presenting capacity of peri toneal cells, but instead up-regulates the allo-antigen-presenting cap acity of peritoneal macrophages.