Emancipator K, Csako G, Elin R J
Clinical Pathology Department, Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland 20892.
Infect Immun. 1992 Feb;60(2):596-601. doi: 10.1128/iai.60.2.596-601.1992.
A chromogenic Limulus amebocyte lysate assay was used to measure the recovery of 1 endotoxin unit of endotoxin per ml. Purified human high-density lipoprotein, low-density lipoprotein, and apolipoprotein A1 (apo A1) at a maximum concentration of 1 g of protein per liter reduced the recovery to less than 40% of baseline in a both dose- and time-dependent manner and in the absence of other serum components. Furthermore, the lapine fever response to a dose of 1 ml of 5-ng/ml endotoxin per kg was reduced by greater than 0.5 degrees C (P less than 0.005) when the solution was preincubated in vitro with 0.5 g of apo A1 per liter. By the Limulus test, a maximum concentration of 0.01 g of apolipoprotein B (apo B) per liter (which contained deoxycholate, a known endotoxin-disaggregating agent) reduced recovery to 0% in a dose- but not time-dependent manner. In heat-inactivated (56 degrees C, 1 h) normal human serum, high-density lipoprotein cholesterol (P less than 0.005) and apo A1 (P less than 0.05) correlated inversely with endotoxin recovery, but, paradoxically, apo B correlated directly with endotoxin recovery (P less than 0.05), while low-density lipoprotein cholesterol showed no significant correlation. INTRALIPID alone had no effect on endotoxin recovery. Addition of a maximum of 10 g of INTRALIPID per liter to 0.0042 g of apo B per liter increased endotoxin recovery from approximately 30 to 80% (P less than 0.001), but addition of INTRALIPID to 0.25 g of apo A1 per liter decreased recovery from approximately 30 to 20% (P less than 0.001). We conclude that (i) lipoproteins are endotoxin inactivators; (ii) this ability of lipoproteins may be modulated by their lipid component (lipid-endotoxin interaction); (iii) apo A1 is capable of directly inactivating endotoxin (protein-endotoxin interaction).
采用显色鲎试剂法检测每毫升含1个内毒素单位的内毒素回收率。纯化的人高密度脂蛋白、低密度脂蛋白和载脂蛋白A1（apo A1），在最高浓度为每升1克蛋白质时，以剂量和时间依赖的方式，在无其他血清成分的情况下，将回收率降低至基线的40%以下。此外，当溶液在体外与每升0.5克apo A1预孵育时，每千克1毫升5纳克/毫升内毒素剂量引起的兔发热反应降低超过0.5摄氏度（P<0.005）。通过鲎试剂试验，每升0.01克载脂蛋白B（apo B）的最大浓度（其中含有已知的内毒素分解剂脱氧胆酸盐）以剂量依赖而非时间依赖的方式将回收率降低至0%。在热灭活（56摄氏度，1小时）的正常人血清中，高密度脂蛋白胆固醇（P<0.005）和apo A1（P<0.05）与内毒素回收率呈负相关，但矛盾的是，apo B与内毒素回收率呈正相关（P<0.05），而低密度脂蛋白胆固醇无显著相关性。单独的英脱利匹特对内毒素回收率无影响。每升向0.0042克apo B中添加最多10克英脱利匹特可使内毒素回收率从约30%提高至80%（P<0.001），但每升向0.25克apo A1中添加英脱利匹特可使回收率从约30%降低至20%（P<0.001）。我们得出结论：（i）脂蛋白是内毒素灭活剂；（ii）脂蛋白的这种能力可能受其脂质成分调节（脂质-内毒素相互作用）；（iii）apo A1能够直接灭活内毒素（蛋白质-内毒素相互作用）。
