Accumulation of oxidized lipid-protein complexes alters phagosome maturation in retinal pigment epithelium

Lipid peroxidation has been implicated in many age-associated disorders including macular degeneration of the retina. We sought to elucidate the mechanism by which accumulation of oxidized LDL (oxLDL) reduces the ability of retinal pigment epithelium (RPE) to process photoreceptor outer segments (OS) as a model of peroxidation-induced disruption of phagocytosis. OxLDL did not reduce the lysosomal hydrolytic capacity of the RPE, but efficiently inhibited processing of various internalized proteins. OxLDL caused a delay in the acquisition of late lysosomal markers by newly formed phagosomes. At the same time, an excessive accumulation of markers of early phagosomal compartments was also observed. The activity of phosphatidylinositol 3-kinase (PI3K) was reduced in phagosomes of the RPE treated with oxLDL. These results suggest that accumulation of oxidized lipid-protein complexes in the RPE impedes phagosome maturation by blocking PI3K recruitment to the phagosomal membrane, leading to delayed processing of internalized OS.Received 24 February 2004; received after revision 12 April 2004; accepted 4 May 2004     

中性红染料摄入法检测人肺泡巨噬细胞吞噬活性探讨

本文作者对中性红染料摄入法的实验条件──肺泡灌洗细胞贴壁时间选择；摄入中性红时间对吞噬活性的影响，及细胞数量时吞噬活性的影响作了探讨．并对肺癌患者肺泡巨噬细胞吞噬活性作了检测．结果表明，此方法用于检测人肺泡巨噬细胞吞噬活性不但指标客观、准确，而且操作简便、省时、微量，适于大量样本检测．     

Investigations of receptor-mediated phagocytosis by hormone-induced (imprinted)Tetrahymena pyriformis

Receptor-mediated endocytosis byTetrahvmena pyriformis was studied using tetramethylrhodamine isothiocyanate-labeled concanavalin A (TRITC-Con A) with fluorescence and confocal microscopy. In the presence of insulin, or 24 h after insulin pretreatment (hormonal imprinting), the binding and uptake of TRITC-Con A increased when compared to controls, owing to the binding of TRITC-Con A to sugar oligomers of insulin recptors. Mannose inhibited the binding of Con A, thus demonstrating the specificity of binding. Histamine, a phagocytosis-promoting factor in mammals andTetrahymena, and galactose, did not influence the uptake of TRITC-Con A.     

Effects of plant lectins on cellular defense reactions of ascidian hemocytes

The effects of plant lectins on the three cellular defense reactions of hemocytes of the solitary ascidian,Halocynthia roretzi (hemocyte aggregation, phagocytosis, and an allogenic reaction), were investigated. Concanavalin A inhibited aggregation, while wheat germ agglutinin and ricin inhibited the allogenic reaction. Neither of the lectins showed inhibitory effects on phagocytosis, but ricin promoted phagocytosis. These effects of the lectins were diminished by the addition of sugars specific for the respective lectins. These results strongly suggest that different surface carbohydrates are involved in the recognition mechanisms of threeH. roretzi cellular defense reactions.     

沼泽红假单胞菌对小鼠免疫功能影响的试验研究

为探讨沼泽红假单胞菌对动物免疫功能的影响,采用不同菌液浓度的沼泽红假单胞菌饲喂小鼠,检测小鼠免疫器官(脾脏和胸腺)实质重量、巨噬细胞吞噬能力、外周血淋巴细胞转化率以及肠黏膜SIgA等指标,分析沼泽红假单胞菌对试验小鼠免疫功能的影响.结果显示,饲喂沼泽红假单胞菌可促进小鼠的体重增长,脾脏和胸腺的重量增加(P0.05);促进机体巨噬细胞吞噬率、淋巴细胞转化率以及肠黏膜SIgA的变化(P0.05).结论:采用沼泽红假单胞菌饲喂小鼠可提高其机体的免疫能力.