Use of the TLX ultracentrifuge for the isolation of different density lipoproteins and effects of freeze/thawing of human plasma before ultracentrifugation

Background: Isolation of different density lipoproteins by ultracentrifugation can require lengthy centrifugation times and freeze/thawing of plasma may influence recovery. Methods: We isolated a range of lipoproteins using a preparative ultracentrifuge and the TLX micro-ultracentrifuge and determined the effect of freeze/thawing of plasma beforehand. Results: In fresh plasma, there was no significant difference in results for small-dense low-density lipoprotein apolipoprotein B (LDL apoB) (density > 1.044 g/mL) or cholesterol at density > 1.006 g/mL. Freeze/thawing had no effect on closely correlated results for small-dense LDL apoB (r = 0.85; p < 0.0001) or high-density lipoprotein (r= 0.93; p < 0.0001). Conclusions: The TLX micro-ultracentrifuge is a reliable alternative to the preparative ultracentrifuge and freeze/thawing has only a small effect on small-dense LDL apoB or high-density lipoprotein cholesterol. Clin Chem Lab Med 2008;46:1285-8.