The Lipids and Lipoproteins of Human Peripheral Lymph, with Observations on the Transport of Cholesterol from Plasma and Tissues into Lymph

Abstract

1. The lipids and lipoproteins of lymph obtained from the dorsum of the foot were examined in seven human subjects. 2. The concentration of total cholesterol in lymph was about one-tenth that in plasma and was significantly correlated with the plasma total cholesterol concentration. The ratio of esterified to total cholesterol in lymph was similar to that in plasma. 3. Triglyceride was detectable in lymph, but the concentration was less than one-tenth that in plasma and was unrelated to the plasma triglyceride concentration. 4. No lipase activity was detectable in lymph, either before or after intravenous injection of heparin. 5. Cholesterol-esterifying activity was detected in four samples of lymph. 6. The major lipoprotein antigens of human plasma (apo-A, apo-B and apo-C) were present in whole lymph, but their distribution in fractions of different density was different from that in plasma. 7. [14C]Cholesterol, injected intravenously, appeared in lymph within 30 min of the injection, indicating that some of the cholesterol in lymph is derived directly from plasma. 8. At intervals greater than 29 days after a single intravenous injection of [14C]-cholesterol, the specific radioactivity of lymph cholesterol was greater than that of plasma cholesterol, indicating that some of the cholesterol in lymph is derived from tissue pools of cholesterol with slow turnover.

Concentrations of Electrophoretic and Size Subclasses of Apolipoprotein A-I–Containing Particles in Human Peripheral Lymph

“…[3][4][5]36 Second, LCAT activity, which catalyzes the conversion of pre-␤ HDLs to CE-rich ␣ HDLs, 4,5 appears to be very low in tissue fluid. 37,38 We have confirmed that human lymph has an extremely low cholesterol esterification rate in vitro (M.N.N. et al, unpublished data, 1999).…”

Statin-exposed vascular smooth muscle cells secrete proteoglycans with decreased binding affinity for LDL

“…Fractions were eluted in 0.4 ml of the same buffer, and the radioactivity of each fraction was determined using liquid scintillation counting. The void volume (V 0 ) of the columns was determined by the elution profile of [ 3 H]DNA, while the total volume (V t ) was determined by the elution profile of free 35 SO 4 (28).…”

“…The remaining medium for each condition was combined with the protease inhibitors benzamidine-HCl (Sigma, 5 mM), 6-aminocaproic acid (Sigma, 100 mM), and PMSF (Sigma, 50 mM) prior to purification. 35 S-labeled proteoglycans were purified from the harvested media using ion-exchange chromatography (23). Media samples containing radiolabeled proteoglycans were applied to DEAESephacel minicolumns equilibrated in urea buffer [8 M urea, 2 mM EDTA, 50 mM Tris-HCl, and 0.5% Triton X-100 (pH 7.5)].…”

Inhibition of Mast Cell–Dependent Conversion of Cultured Macrophages Into Foam Cells With Antiallergic Drugs

“…4 In the skin, as in other extrahepatic tissues, the concentration of LDL is much lower (only 1/10) than in the corresponding blood plasma. 40 Thus, in the skin, mast cell activation leads to a rapid increase of LDL concentration in the extracellular fluid and so creates conditions suitable for the binding of LDL to exocytosed heparin proteoglycans. 4 By blocking this increase, a mast cell-stabilizing drug would have an additional benefit in preventing mast cell-dependent foam cell formation in the skin.…”