Pradhan D, Williamson P, Schlegel R A
Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park 16802.
Mol Membr Biol. 1994 Jul-Sep;11(3):181-7. doi: 10.3109/09687689409162237.
In the plasma membrane of erythrocytes, the phospholipids are asymmetrically distributed between the two leaflets of the bilayer. Erythrocytes that have lost this asymmetric distribution are more readily phagocytosed in vitro by macrophages. Surface exposure of phosphatidylserine (PS), normally restricted to the inner leaflet of the bilayer, has been suggested as a signal by which macrophages recognize erythrocytes. To test whether lipid-symmetric erythrocytes are recognized by this mechanism, artificial lipid vesicles made of PS were tested for their ability to inhibit phagocytosis. J774 mouse macrophages, which preferentially phagocytose PS vesicles, were incubated with a mixture of lipid-symmetric erythrocytes and vesicles. PS vesicles reduced phagocytosis of lipid-symmetric erythrocytes to the level of lipid-asymmetric erythrocytes, whereas phosphatidylcholine vesicles had only a limited effect. These results support a role for PS in recognition of erythrocytes and lend credence to the more general hypothesis that PS is involved in the recognition of all blood cells by the reticuloendothelial system.
在红细胞的质膜中，磷脂在双层膜的两个小叶之间不对称分布。失去这种不对称分布的红细胞在体外更容易被巨噬细胞吞噬。磷脂酰丝氨酸（PS）通常局限于双层膜的内小叶，其表面暴露被认为是巨噬细胞识别红细胞的信号。为了测试脂质对称的红细胞是否通过这种机制被识别，对由PS制成的人工脂质囊泡抑制吞噬作用的能力进行了测试。优先吞噬PS囊泡的J774小鼠巨噬细胞与脂质对称的红细胞和囊泡混合物一起孵育。PS囊泡将脂质对称红细胞的吞噬作用降低到脂质不对称红细胞的水平，而磷脂酰胆碱囊泡的作用有限。这些结果支持了PS在红细胞识别中的作用，并为更普遍的假设提供了可信度，即PS参与网状内皮系统对所有血细胞的识别。
