EFFECTS OF MEMBRANE-CHARACTERISTICS ON CYTOKINE PRODUCTION BY MONONUCLEAR-CELLS IN REGULAR HEMODIALYSIS-PATIENTS

To determine the relationship between haemodialysis and cytokine produ ction, the effects of solute permeability and biocompatibility of dial ysis membranes on cytokine production by mononuclear cells were evalua ted. Eighteen stable haemodialysis patients were divided into three gr oups and underwent haemodialysis under the same conditions except for the dialysis membrane used. Endotoxin in dialysate remained at concent rations of 10 pg/ml or less throughout the study. Haemodialysis was pe rformed for a total of 6 weeks. Group A used a regenerated cellulose l ow-flux membrane during the first 2 weeks, a regenerated cellulose hig h-flux membrane during the next 2 weeks and a polymethylmethacrylate ( PMMA) high-flux membrane during the last 2-week period, while Group B used the regenerated low-flux cellulose membrane first, followed by th e PMMA low-flux membrane and PMMA high-flux membrane. Group C used the same membrane throughout the 6-week study period. Peripheral mononucl ear cells were sampled before, 30 min after the start and upon complet ion of the final dialysis session and incubated for 18 h in the presen ce and absence of lipopolysaccharide (LPS) stimulation. Tumour necrosi s factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta) and IL-6 co ncentrations in the supernatant and cell lysate were determined. In al l groups, cytokine production just before the final dialysis using eac h membrane was comparable regardless of the presence or absence of LPS stimulation. LPS-stimulated TNF-alpha production decreased significan tly 30 min after the start of dialysis compared to the predialysis bas eline. This change was not affected by the type of membrane used. When regenerated cellulose membranes were used, both LPS-stimulated and no n-stimulated IL-1 beta and IL-6 production decreased significantly 30 min after the start of dialysis compared to the baseline. When PMMA me mbrane was used, these decreases were seen only when stimulated by LPS . TNF-alpha, IL-1 beta and IL-6 production returned to the baseline up on completion of dialysis. These findings suggest that transient decre ases in cytokine production during dialysis are more marked when regen erated cellulose membranes are used than when PMMA membranes are used. However, biocompatibility and solute permeability of membranes do not seem to significantly affect cytokine production by mononuclear cells in mid-term (about 2 weeks).