Abstract. A number of bacterial cytokine-inducing substances (CIS) such as lipopolysaccharides (LPS) and exotoxins have been detected in dialysate and may contribute to inflammation in hemodialysis patients. Short DNA fragments, oligodeoxynucleotides (ODN) of 6 to 20 nucleotides, are able to bind to Toll-like receptors and are stimulatory on immune cells. ODN induce natural killer cell activity and induce IFN-␥, TNF-␣, and IL-6 from mononuclear cells. The presence of ODN in dialysate samples and bacterial cultures was investigated. ODN were extracted from fluids by adsorption to reverse-phase columns. ODN were detected in 18 of 20 investigated dialysate samples, in eight of 10 reverse-osmosis water samples, and in all cultures from various bacterial strains. The presence of bacterial DNA in dialysate was confirmed by PCR specific for bacterial tRNA gene sequences. Saline for intravenous use contained 0.02 Ϯ 0.01 g/ml DNA, dialysate samples contained 0.28 Ϯ 0.02 g/ml, and Pseudomonas cultures contained 1.0 Ϯ 0.03 g/ml DNA. ODN from bacterial cultures were only partially removed by ultrafiltration and were able to diffuse through regular high-flux dialyzer membranes. Synthetic cytosine-guanosine dinucleotide-containing ODN were able to induce IL-6 in human mononuclear cells. It is concluded that short bacterial-derived DNA fragments are present in clinically used fluids, e.g., dialysate. These fragments are of sufficient small size to pass through dialyzer membranes. Bacterial DNA fragments may be an overlooked factor contributing to inflammation in hemodialysis patients.

High permeability hemofiltration is a new approach in the adjuvant therapy of sepsis that facilitates the elimination of cytokines. HP-HF alternating with conventional hemofiltration is well tolerated. Further studies are needed to analyze whether HP-HF is able to mitigate the course of sepsis.

High cut-off haemofilters achieve high clearances for inflammatory IL-6 and TNF-alpha. Due to the high protein loss in haemofiltration, dialysis in combination with balanced protein substitution seems to be a suitable approach for clinical trials.

The commercial application of membranes in dialysis treatment has started already 40 years ago. Today, dialysis is the application in medicine using the largest number of membrane surface area per year. Integration of the membrane production process into dialyzer manufacturing was the key element in the successful transition from small scale production to large scale dialyzer manufacturing. Automatization techniques are heavily integrated into this process to fulfill the high quality and safety demands in medical technology. This paper gives an overview on the different membrane applications in medical industry. The material selection for manufacturing dialysis membranes and the different membrane morphologies are discussed. In the second part the different manufacturing steps in dialyzer production are presented.