IN-VITRO CHARACTERIZATION OF A MEMBRANE-BASED LOW-DENSITY-LIPOPROTEINAFFINITY ADSORPTION DEVICE

The objective of this study was to explore the use of microporous memb ranes as an alternative substrate to porous beads in affinity adsorpti on of low-density lipoprotein (LDL) for therapeutic purposes. Flat she et immunoaffinity membranes containing a polyclonal antibody preparati on were utilized as the affinity substrate. The antibody was covalentl y immobilized to the surface through a poly(ethylene glycol) (PEG) spa cer. Equilibrium adsorption of LDL from plasma was measured. Adsorptio n from plasma and elution of bound LDL using citrate buffer were studi ed as a function of flow rate. Specific capacity was as great as 2 mg apolipoprotein B per milliliter membrane volume. The superior transpor t properties of the membrane allowed rapid adsorption and regeneration , which translated to a large number of adsorptive cycles that can be performed within a given treatment time. On the basis of in vitro perf ormance characteristics, it is estimated that an immunoaffinity membra ne device can provide a reduction in patient plasma LDL concentration comparable to that provided by packed columns, but with almost an 80% reduction in the device volume.