Peritoneal macrophage beta-2 microglobulin production and bacterial peritonitis in CAPD patients. To evaluate the role of bacterial peritonitis in peritoneal macrophage (PM) Beta-2 Microglobulin (B2M) production, and its relationship with PM Interleukin-1 (IL-1) and Leukotriene B4 (LTB4) release, the authors studied 20 CAPD patients (10 with peritonitis): 1. in vivo plasma and peritoneal dialysis effluent (PDE) B2M, IL-1, and LTB4 levels; 2. in vitro B2M, IL-1, and LTB4 release by PM. Values were compared with those seen in the plasma or with peripheral blood monocytes of 30 hemodialysis (HD) patients (10 treated with Cuprophan [CU]; 10 with Polyacrylonitrile [PAN]; and 10 with Cellulose Acetate [CA]). Results showed that in CAPD patients with bacterial peritonitis B2M, IL-1 and LTB4 concentrations in the PDE were significantly higher than those seen in CAPD patients without peritonitis, or in the plasma of HD patients treated with PAN or CA, but were similar to those seen in HD patients treated with CU. At the same time, in vitro PM from CAPD patients with bacterial peritonitis produced more B2M, IL-1, and LTB4, than did PM from CAPD patients without peritonitis, or peripheral blood monocytes from HD patients treated with PAN or CA. The authors conclude that in CAPD patients, bacterial peritonitis is able to induce PM B2M production, probably via a cytokine mediated process, which may be analogous to what occurs with peripheral blood monocytes of HD patients treated with CU. 