The effect of membrane characteristics on tumour necrosis factor kinetics during haemodialysis

We measured serum beta 2-M and TNF alpha before and after a 4-h haemodialysis performed on two membranes with different characteristics, either cuprophane (n = 40) or polyacrylonitrile (AN69) (n = 31). Kinetic studies including determinations at 0, 15, 30, 60 and 240 min were also performed during haemodialysis sessions on cuprophane (n = 14) and AN69 (n = 12). After a 240-min haemodialysis, TNF alpha increased on cuprophane (21.95 +/- 3.46 to 37.20 +/- 4.60 pg/ml, P less than 0.001) but remained stable on AN69 (16.70 +/- 2.60 to 19.90 +/- 2.90 pg/ml, NS). Kinetic studies revealed that on cuprophane, beta 2-M increased progressively from 40.72 +/- 4.41 to 45.71 +/- 4.77 mg/l (P less than 0.001) at 240 min with a significant increase already noted at 60 min. TNF alpha remained stable during the first 60 min but increased significantly at 240 min (34.14 +/- 6.60 to 49.71 +/- 8.78 pg/ml, P less than 0.001). The percentage increment in TNF alpha (50.5%) was significantly greater at 240 min than the percentage increment in beta 2-M (13.4%), a finding suggestive of net generation of TNF alpha. On AN69, beta 2-M decreased progressively from 31.82 +/- 2.70 to 27.30 +/- 2.26 mg/l (P less than 0.001). TNF alpha decreased transiently at 15 min but returned subsequently to control values (0 and 240 min: 25.00 +/- 3.81 and 29.75 +/- 3.59 pg/ml respectively, NS). Our data suggest a net release of TNF alpha during cuprophane but not during polyacrylonitrile haemodialysis. This release might play a role in the stimulation of beta 2-M production and thus in the genesis of dialysis amyloidosis.