Do cytokine-inducing substances penetrate through dialysis membranes and stimulate monocytes?
Does a relatively low concentration of endotoxin in dialysate, seen in our clinical dialysis, enhance cytokine production of monocytes across high-flux membranes? Several investigators using extremely high concentrations of endotoxin in dialysate maintain that it does. In vitro experiments in this study were conducted to clarify this. Peripheral blood monocytes were isolated from healthy volunteers and incubated for 20 hours. The incubation medium was made of back-filtrates obtained either from Pseudomonas-contaminated water with endotoxin concentration of 621 pg/ml or water with 10 ng/ml or 1 microgram/ml of lipopolysaccharide (LPS), by passing it through a high-flux membrane dialyzer. Endotoxin free water and addition of LPS (0.01 to 10 ng/ml) were used as a negative and positive control. Interleukin-1 beta (IL-1 beta), IL-6 and tumor necrosis factor alpha (TNF alpha) were measured. Back-filtrate from Pseudomonas-contaminated water did not enhance cytokine production, while 50 pg/ml
