Bratosin D, Leszczynski S, Sartiaux C, Fontaine O, Descamps J, Huart J J, Poplineau J, Goudaliez F, Aminoff D, Montreuil J
National Institute of Biological Science Research and Development, Bucharest, Rumania.
Cytometry. 2001 Dec 15;46(6):351-6. doi: 10.1002/cyto.10005.
In vivo phagocytosis of senescent red blood cells (RBCs) by macrophages occurs 120 days after their release into the circulation. It depends on two sequential signals that trigger phagocytosis: (1) desialylation of membrane glycoconjugates with the exposure of the penultimate beta-galactosyl residues and (2) exposure of phosphatidylserine in the membrane outer leaflet. Leukodepleted and nonleukodepleted RBCs were compared using flow cytometric procedures to determine whether the in vitro deterioration of RBCs during storage might be attributable to an identical mechanism of desialylation induced by leukocyte neuraminidases, resulting in exposure of beta-galactosyl and subsequently phosphatidylserine residues - signals of senescent RBCs. Without prior leukodepletion, stored RBCs showed an increased population of senescent RBCs (using light scatter measurements), extensive desialylation with the exposure of beta-galactosyl residues (using specific fluorescein isothiocyanate [FITC]-lectins), significant exposure of phosphatidylserine in the outer leaflet of the RBC membrane (using FITC-annexin V), and extensive in vitro phagocytosis (using PKH-26-labeled RBCs). There were minimal changes observed with the leukodepleted RBCs. These results lead to the conclusion that leukocyte enzymes, including neuraminidases, are definitive contributers to the desialylation of RBCs during storage and to the exposure of phosphatidylserine residues. These deleterious effects resulting from highly active leukocyte enzymes are preventable by prior leukodepletion of the stored RBCs. Previously developed flow cytometric procedures to detect in vivo "RBC senescence" have been applied and proved to be reliable criteria to monitor the viability of stored RBCs.
巨噬细胞对衰老红细胞（RBC）的体内吞噬作用发生在其释放到循环系统120天后。这取决于触发吞噬作用的两个连续信号：（1）膜糖缀合物的去唾液酸化，伴随倒数第二个β-半乳糖基残基的暴露；（2）膜外小叶中磷脂酰丝氨酸的暴露。使用流式细胞术程序比较了去除白细胞和未去除白细胞的红细胞，以确定储存期间红细胞在体外的劣化是否可能归因于白细胞神经氨酸酶诱导的相同去唾液酸化机制，从而导致β-半乳糖基暴露，随后磷脂酰丝氨酸残基暴露——这是衰老红细胞的信号。在没有预先去除白细胞的情况下，储存的红细胞显示衰老红细胞群体增加（使用光散射测量），广泛的去唾液酸化并伴有β-半乳糖基残基的暴露（使用特异性异硫氰酸荧光素[FITC]凝集素），红细胞膜外小叶中磷脂酰丝氨酸的显著暴露（使用FITC-膜联蛋白V），以及广泛的体外吞噬作用（使用PKH-26标记的红细胞）。去除白细胞的红细胞观察到的变化最小。这些结果得出结论，包括神经氨酸酶在内的白细胞酶是储存期间红细胞去唾液酸化和磷脂酰丝氨酸残基暴露的决定性因素。通过预先去除储存红细胞中的白细胞，可以预防这些由高活性白细胞酶引起的有害影响。先前开发的用于检测体内“红细胞衰老”的流式细胞术程序已得到应用，并被证明是监测储存红细胞活力的可靠标准。
