Mironova M, Virella G, Virella-Lowell I, Lopes-Virella M F
Ralph H. Johnson Department of Veterans Affairs Medical Center, Medical University of South Carolina, Charleston 29401-5799, USA.
Clin Immunol Immunopathol. 1997 Oct;85(1):73-82. doi: 10.1006/clin.1997.4404.
Antibodies to oxidized LDL (ox-LDL) and LDL-containing immune complexes (LDL-IC) have been reported to be associated with the presence or progression of arteriosclerosis. We screened for anti-modified LDL antibodies and isolated soluble IC by precipitation with 3.5% (w/v) polyethylene glycol (PEG) 6000 in two groups. The patient group was constituted by 16 insulin-dependent diabetes mellitus subjects free of macrovascular complications. The control group was constituted by 16 healthy, age-, gender-, race-, and body mass index-matched nondiabetic subjects. We detected anti-ox-LDL antibodies and anti-malondialdehyde-modified LDL antibodies with similar levels in patients and controls, while the levels of anti-glycated LDL antibodies were very low, but slightly higher in diabetics than in healthy controls. Isolated LDL-IC were adsorbed to red blood cells (RBC) and incubated with human macrophages for 18 hr at 37 degrees C. Under those experimental conditions, RBC-adsorbed IC are taken up by macrophages but the RBC remain intact and are not ingested. Slightly higher levels of cholesteryl ester (CE) accumulation were measured in macrophages incubated with RBC to which we adsorbed IC isolated from diabetics (15.4 +/- 2.5 micrograms/mg of protein, mean +/- SEM) than in macrophages incubated with IC isolated from controls (12.5 +/- 1.6 micrograms/mg of protein, mean +/- SEM), but the difference did not reach statistical significance. PEG-precipitable IC isolated from both normal and diabetic subjects led, in some instances, to the transformation of macrophages into foam cells. Significant correlations were observed between CE accumulation and the content of apo B (P < 0.0001), total cholesterol (P = 0.0004), IgG (P = 0.015), and IgA (P = 0.015) in the isolated IC. The correlation between CE accumulation and the content of apo B in isolated IC was stronger in diabetics than in the control group (r = 0.759 vs r = 0.500). Fractionation of isolated IC in immobilized protein A/G yielded immunoglobulin-rich fractions which contained cholesterol and IgG anti-ox-LDL antibodies. The cholesterol content of these fractions was significantly correlated (P = 0.001) with CE accumulation. In conclusion, both diabetics and normal individuals have circulating IC whose atherogenic potential appears to be related to the presence of LDL and antibodies of the IgG and IgA isotypes.
据报道，氧化型低密度脂蛋白（ox-LDL）抗体和含低密度脂蛋白的免疫复合物（LDL-IC）与动脉硬化的存在或进展有关。我们在两组中通过用3.5%（w/v）聚乙二醇（PEG）6000沉淀来筛选抗修饰低密度脂蛋白抗体并分离可溶性免疫复合物。患者组由16名无大血管并发症的胰岛素依赖型糖尿病患者组成。对照组由16名年龄、性别、种族和体重指数相匹配的健康非糖尿病受试者组成。我们检测到患者和对照组中抗ox-LDL抗体和抗丙二醛修饰低密度脂蛋白抗体水平相似，而抗糖化低密度脂蛋白抗体水平非常低，但糖尿病患者略高于健康对照组。分离出的LDL-IC吸附到红细胞（RBC）上，并在37℃下与人巨噬细胞孵育18小时。在这些实验条件下，RBC吸附的免疫复合物被巨噬细胞摄取，但RBC保持完整且未被吞噬。与用从对照组分离的免疫复合物孵育的巨噬细胞相比，用从糖尿病患者分离的免疫复合物吸附的RBC孵育的巨噬细胞中胆固醇酯（CE）积累水平略高（15.4±2.5微克/毫克蛋白质，平均值±标准误），但差异未达到统计学显著性。从正常人和糖尿病患者分离的PEG可沉淀免疫复合物在某些情况下会导致巨噬细胞转变为泡沫细胞。在分离的免疫复合物中，观察到CE积累与载脂蛋白B含量（P<0.0001）、总胆固醇（P = 0.0004）、IgG（P = 0.015）和IgA（P = 0.015）之间存在显著相关性。糖尿病患者中分离的免疫复合物中CE积累与载脂蛋白B含量之间的相关性比对照组更强（r = 0.759对r = 0.500）。固定化蛋白A/G对分离的免疫复合物进行分级分离得到富含免疫球蛋白的级分，其中含有胆固醇和抗ox-LDL IgG抗体。这些级分的胆固醇含量与CE积累显著相关（P = 0.001）。总之，糖尿病患者和正常个体都有循环免疫复合物，其致动脉粥样硬化潜力似乎与LDL以及IgG和IgA同种型抗体的存在有关。
