Reduced secretion of IL-1 beta by peritoneal cells from patients on continuous ambulatory peritoneal dialysis

The endogenous and lipopolysaccharide stimulated interleukin (IL)-1 beta production in vitro by peritoneal monocytes/macrophages from patients on continuous ambulatory peritoneal dialysis (CAPD) was examined during episodes of infection and inflammation. Measurement of immunoreactive IL-1 beta and bioactive IL-1 in both supernatants and cell lysates after culture for 18 h revealed that these cells secreted a significantly lower proportion of total IL-1 than that measured for elutriated blood monocytes. For the inflammatory peritoneal cells, the proportion of total IL-1 beta that was cell-associated resembled that reported for more differentiated pulmonary alveolar macrophages and for adherent monocytes cultured for 18 h prior to stimulation. A similar reduced ability to secrete IL-1 beta was detected for unfractionated peritoneal cells from CAPD patients without peritonitis upon direct comparison with the IL-1 beta production by blood mononuclear cells from the same patients. These results suggested that at a time when a pro-inflammatory response by extravasated host monocytes/macrophages was required by CAPD patients with peritonitis, only a minor proportion of total IL-1 beta would be available extracellularly. This study highlights the rapidity with which extravasated monocytes lose their ability to secrete IL-1 beta and raises the possibility that an important site of utilization of IL-1 beta in vivo may be intracellular in its location.