Lipoproteins removed from serum and plasma by membrane filtration

Tangential (crossflow) filtration of a plasma/serum mixture through 0.2 micrometer-poresize polycarbonate track-etch membrane filters (PC) at pressures less than 10 psi removes low density lipoproteins (LDL) and very low density lipoproteins (VLDL) but not high density lipoproteins (HDL) from the filtrate. At pressures greater than 10 psi all lipoproteins pass through the PC. Once the filters have been intruded with LDL and VLDL those lipoproteins continue to pass the filters despite subsequent reduction in differential pressure below 10 psi.