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Available under a Creative Commons Attribution Non-Commercial Share Alike 4.0 International Licence


1.4 CHEMICAL SCIENCES, Biochemistry and molecular biology


Microparticles are sub-micron, membrane-bound particles released from virtually allcells and which are present in the circulation. In several autoimmune disorders their amountand composition in the circulation is altered. Microparticle surface protein expression has beenexplored as a differentiating tool in autoimmune disorders where the clinical pictures can overlap.Here, we examine the utility of a novel lipid-based marker—microparticle cholesterol, present in allmicroparticles regardless of cellular origin—to distinguish between rheumatoid arthritis (RA) andsystemic lupus erythematosus (SLE). We first isolated a series of microparticle containing lipoproteindeficient fractions from patient and control plasma. There were no significant differences in thesize, structure or protein content of microparticles isolated from each group. Compared to controls,both patient groups contained significantly greater amounts of platelet and endothelial cell-derivedmicroparticles. The cholesterol content of microparticle fractions isolated from RA patients wassignificantly greater than those from either SLE patients or healthy controls. Our data indicate thatcirculating non-lipoprotein microparticle cholesterol, which may account for 1–2% of measuredcholesterol in patient samples, may represent a novel differentiator of disease, which is independentof cellular origin