chylomikronach

Chylomikronach, the Polish term for chylomicrons, are the largest and least dense lipoprotein particles in human plasma. They are formed in the enterocytes of the small intestine after a fat-containing meal. Their core is composed mainly of triglycerides, surrounded by a monolayer of phospholipids and apolipoproteins, with apolipoprotein B-48 as a defining component. The assembly of chylomicrons requires microsomal triglyceride transfer protein (MTP) to re-esterify absorbed lipids and package them with apoB-48.

Chylomicrons are secreted into the lymphatic system through intestinal lacteals, bypassing the hepatic portal circulation, and enter the bloodstream via the thoracic duct. In the circulation, lipoprotein lipase (LPL) on capillary endothelium—activated by apolipoprotein C-II—hydrolyzes triglycerides, releasing free fatty acids for uptake by adipose tissue and muscle. As triglycerides are depleted, chylomicrons become remnant particles enriched in cholesterol esters. These remnants are cleared rapidly from the blood, primarily by the liver through receptors that recognize apolipoprotein E.

Role and clinical relevance: Chylomicrons deliver dietary lipids to tissues, contributing to energy supply and the distribution of fat-soluble vitamins. They are distinct from hepatic very-low-density lipoproteins (VLDL) and are predominantly dietary in origin. Disorders affecting chylomicrons include abetalipoproteinemia, caused by defects in apoB-48-containing lipoprotein production (often MTP deficiency), leading to fat malabsorption and related complications. Familial hyperchylomicronemia, due to LPL or apoC-II deficiencies, results in elevated postprandial triglycerides and risk of pancreatitis. In healthy individuals, chylomicron levels rise after meals and fall during fasting.