L-fucose residues on cellulose-based dialysis membranes: quantification of membrane-associated L-fucose and analysis of specific lectin binding.

Contact of mononuclear human leukocytes with cellulose dialysis membranes may result in complement-independent cell activation, i.e. enhanced synthesis of cytokines, prostaglandins and an increase in beta 2-micro-globulin synthesis. Cellular contact activation is specifically inhibited by the monosaccharide L-fucose suggesting that dialysis membrane associated L-fucose residues are involved in leukocyte activation. In this study we have detected and quantitated L-fucose on commercially-available cellulose dialysis membranes using two approaches. A sensitive enzymatic fluorescence assay detected L-fucose after acid hydrolysis of flat sheet membranes. Values ranged from 79.3 +/- 3.6 to 90.2 +/- 5.0 pmol cm-2 for Hemophan or Cuprophan respectively. Enzymatic cleavage of terminal alpha-L-fucopyranoses with alpha-L-fucosidase yielded 7.7 +/- 3.3 pmol L-fucose per cm2 for Cuprophan. Enzymatic hydrolysis of the synthetic polymer membranes AN-69 and PC-PE did not yield detectable amounts of L-fucose. In a second approach, binding of the fucose specific lectins of Lotus tetragonolobus and Ulex europaeus (UEAI) demonstrated the presence of biologically accessible L-fucose on the surface of cellulose membranes. Specific binding was observed with Cuprophan, and up to 2.6 +/- 0.3 pmol L-fucose per cm2 was calculated to be present from Langmuir-type adsorption isotherms. The data presented are in line with the hypothesis that surface-associated L-fucose residues on cellulose dialysis membranes participate in leukocyte contact activation.