Tobias P S, Ulevitch R J
J Immunol. 1983 Oct;131(4):1913-6.
When Salmonella minnesota R595 lipopolysaccharide (LPS) is mixed with serum, the LPS eventually forms a complex with high density lipoprotein (HDL). Complex formation is conveniently followed by CsCl equilibrium density gradient centrifugation. When mixing 10 micrograms LPS with normal rabbit serum (NRS) at 37 degrees C in the presence of 20 mM EDTA, the half-life for LPS binding to HDL is typically 2 to 3 min. When the same experiment is performed with the use of acute phase rabbit serum (APRS; collected 24 hr post-induction with silver nitrate), the half-life for LPS binding to HDL is typically 40 to 100 min. Thus LPS binding to HDL occurs some 20- to 40-fold slower in APRS than in NRS. Two other phenomena have been found, the time dependencies of which correlate well with the time dependency of LPS binding to HDL in APRS. If LPS-APRS reaction mixtures are cooled to 4 degrees C shortly after mixing and are dialyzed against 2.5 mM HEPES, 15 mM NaCl, pH 7.4 buffer, LPS is recovered in the washed precipitates ("euglobulin precipitate") if, and only if, the LPS-HDL binding reaction is not complete. The amount of LPS in the precipitate correlates well with the amount of LPS that has not bound to HDL. The second phenomenon we observe is that the LPS-containing euglobulin precipitate prepared from LPS-acute phase serum reaction mixtures shortly after mixing also contains a protein, gp60, the concentration of which in the euglobulin precipitate correlates well with the amount of LPS in the precipitate. Thus three phenomena are kinetically well correlated in APRS: the degree of binding of LPS to HDL, the degree of appearance of LPS in a euglobulin fraction, and the concentration of protein gp60 in the euglobulin fraction. We were unable to precipitate gp60 from APRS in the absence of LPS, from APRS after the LPS has fully bound to HDL, or from normal serum in the presence or absence of LPS. The known properties of gp60 are not reminiscent of any other known acute phase reactant. These data demonstrate that APRS contains acute phase reactants that interact with LPS to modify its buoyant density, its solubility, and the rate of its binding to HDL.
当明尼苏达沙门氏菌R595脂多糖（LPS）与血清混合时，LPS最终会与高密度脂蛋白（HDL）形成复合物。复合物的形成可通过CsCl平衡密度梯度离心方便地进行跟踪。在20 mM EDTA存在下，于37℃将10微克LPS与正常兔血清（NRS）混合时，LPS与HDL结合的半衰期通常为2至3分钟。当使用急性期兔血清（APRS；用硝酸银诱导后24小时收集）进行相同实验时，LPS与HDL结合的半衰期通常为40至100分钟。因此，在APRS中LPS与HDL的结合速度比在NRS中慢约20至40倍。还发现了另外两种现象，它们的时间依赖性与APRS中LPS与HDL结合的时间依赖性密切相关。如果LPS - APRS反应混合物在混合后不久冷却至4℃，并对2.5 mM HEPES、15 mM NaCl、pH 7.4缓冲液进行透析，那么只有在LPS - HDL结合反应未完成的情况下，LPS才会在洗涤后的沉淀物（“优球蛋白沉淀物”）中回收。沉淀物中LPS的量与未与HDL结合的LPS量密切相关。我们观察到的第二个现象是，在混合后不久从LPS - 急性期血清反应混合物中制备的含LPS的优球蛋白沉淀物还含有一种蛋白质gp60，其在优球蛋白沉淀物中的浓度与沉淀物中LPS的量密切相关。因此，在APRS中有三种现象在动力学上密切相关：LPS与HDL的结合程度、LPS在优球蛋白部分中的出现程度以及优球蛋白部分中蛋白质gp60的浓度。在没有LPS的情况下，我们无法从APRS中沉淀出gp60，在LPS已完全与HDL结合后的APRS中也无法沉淀出gp60，在有或没有LPS的正常血清中同样无法沉淀出gp60。gp60的已知特性与任何其他已知的急性期反应物都不相似。这些数据表明，APRS含有急性期反应物，它们与LPS相互作用以改变其浮力密度、溶解度及其与HDL结合的速率。
