Influence of the charge of low molecular weight proteins on their efficacy of filtration and/or adsorption on dialysis membranes with different intrinsic properties.
Hemodialysis membranes eliminate by filtration low-molecular-weight toxic metabolites (urea and creatinine) with minimum interactions between blood components and the membrane itself. However, the ability of a membrane to adsorb specific proteins could be beneficial if the accumulation of these same proteins is implicated in the genesis of a pathological condition. Beta-amyloidosis which accompanies the elevation of beta2-microglobulin (11.8 kDa) in the plasma of dialysed patients is one such condition (Biochem. Biophys. Res. Commun. 129 (3) (1985) 701-706: Lancet 1 (1986) 1240-1311). To determine whether increases in plasma beta2-microglobulin levels were due to differences in filtration efficacy of the membrane used and/or to certain characteristics of this protein, e.g. its charge (pI 5.7) the adsorption and filtration of [3H] beta2-microglobulin and [3H] lysozyme of similar MW 14.5 kDa, but pI: 10.8 were compared on different membranes. It was found that, neither [3H] beta2-microglobulin nor [3H] lysozyme are removed by cuprophan, whereas over 75% of beta2-microglobulin is removed by filtration on polyacrylonitrile, polyacrylonitrile-polyethyleneimine, polysulfone and >95% by adsorption to polymethylmethacrylate-BK. For lysozyme, removal by adsorption is >95% on polyacrylonitrile and polyacrylonitrile-polyethyleneimine, 72% on polymethylmethacrylate-BK and by filtration is 95% on polysulfone. Hemodialysis membranes must therefore not simply be considered as filters of low-molecular-weight metabolites but should be equally assessed for their capacity to eliminate potentially deleterious low-molecular-weight plasma proteins.
Moachon
N
N
Laboratoire d'Immunochimie, INSERM 4329, Faculté de Médecine Lyon-Sud, Université Claude Bernard, Lyon I, Oullins, France.
Boullange
C
C
Fraud
S
S
Vial
E
E
Thomas
M
M
Quash
G
G
D000327:Adsorption; D000686:Amyloidosis / Q000209:etiology; D001672:Biocompatible Materials; D003956:Dialysis / Q000379:methods; D005374:Filtration; D006801:Humans; D007700:Kinetics; D008567:Membranes, Artificial; D008970:Molecular Weight; D009113:Muramidase / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D006435:Renal Dialysis / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D013329:Structure-Activity Relationship; D001613:beta 2-Microglobulin / Q000097:blood
D001672:Biocompatible Materials; D008567:Membranes, Artificial; D011506:Proteins; D001613:beta 2-Microglobulin; D009113:Muramidase