Isolation of serum chylomicrons prior to density gradient ultracentrifugation of other serum lipoprotein classes.

A method for the removal of serum chylomicrons before density gradient ultracentrifugation of the other serum lipoproteins using an SW 41 swinging bucket rotor is presented. In a preliminary spin, the chylomicrons with an Sf greater than 400 X 10(-13) s float to the top of the gradient, whereas the other lipoproteins are retained in the infranatant fraction. After removal of the chylomicrons, the other serum lipoproteins are subsequently fractionated by isopycnic density gradient ultracentrifugation. Analysis of the separated lipoprotein fractions suggested that this procedure permits isolation of a chylomicron fraction consisting solely of chylomicrons but that the very low density lipoprotein fraction subsequently isolated also contains chylomicrons or chylomicron remnants with an Sf less than 400 X 10(-13) s, and that there is considerable overlap in flotation rate and particle size of very low density lipoproteins and chylomicrons.