Ballas S K, Bator S M, Aubuchon J P, Marsh W L, Sharp D E, Toy E M
Cardeza Foundation for Hematologic Research, Department of Medicine, Thomas Jefferson University Hospital Blood Bank, Philadelphia, Pennsylvania.
Transfusion. 1990 Oct;30(8):722-7. doi: 10.1046/j.1537-2995.1990.30891020333.x.
McLeod red cells (RBCs) lack Kx antigens and have weak expression of the Kell antigens. Individuals who carry the McLeod phenotype have acanthocytic RBCs and a compensated hemolytic state. To elucidate the role of the protein on which the Kx antigens reside in maintaining membrane deformability, the rheologic properties of McLeod RBCs were determined by ektacytometry. RBCs were obtained from normal individuals and from four patients with McLeod syndrome. Osmotic gradient deformability profiles of McLeod RBCs showed decreased whole cell deformability. Resealed ghosts from McLeod RBCs also showed decreased deformability, partly because of the decreased cell surface area and partly because of an intrinsic membrane stiffness in this syndrome. For the measurement of membrane mechanical stability, resealed ghosts were subjected to constant high shear stress in the ektacytomer, and deformability was recorded continuously as the deformable ghosts fragmented into rigid spherical vesicles. Membranes from McLeod RBCs showed a noticeable increase in mechanical stability. Acquired causes of acanthocytosis, such as liver disease, did not cause the rheologic abnormalities observed in McLeod cells. Other abnormalities noted in McLeod RBCs were decreased RBC potassium content and an increased number of dense RBCs, as determined by centrifugation on a discontinuous density gradient. The data indicate that McLeod RBCs are rigid and have decreased surface area and that their membranes are intrinsically rigid with increased mechanical stability. These abnormalities may account for the reduced RBC survival observed in McLeod syndrome. The protein that carries the Kx surface antigen seems to be required for the maintenance of the normal physical function of RBC skeletal proteins.
麦克劳德红细胞（RBCs）缺乏Kx抗原，且凯尔抗原表达较弱。携带麦克劳德表型的个体具有棘形红细胞和代偿性溶血状态。为了阐明Kx抗原所驻留的蛋白质在维持膜变形性中的作用，通过激光衍射血细胞分析法测定了麦克劳德红细胞的流变学特性。红细胞取自正常个体和四名麦克劳德综合征患者。麦克劳德红细胞的渗透梯度变形性曲线显示全细胞变形性降低。麦克劳德红细胞重新封闭的血影也显示变形性降低，部分原因是细胞表面积减小，部分原因是该综合征中固有的膜僵硬。为了测量膜的机械稳定性，将重新封闭的血影在激光衍射血细胞分析仪中施加恒定的高剪切应力，并在可变形血影破碎成刚性球形囊泡时连续记录变形性。麦克劳德红细胞的膜显示出机械稳定性显著增加。获得性棘形红细胞增多症的病因，如肝病，并未导致在麦克劳德细胞中观察到的流变学异常。通过在不连续密度梯度上离心测定，麦克劳德红细胞中其他注意到的异常是红细胞钾含量降低和致密红细胞数量增加。数据表明，麦克劳德红细胞僵硬且表面积减小，其膜固有僵硬且机械稳定性增加。这些异常可能解释了在麦克劳德综合征中观察到的红细胞存活减少。携带Kx表面抗原的蛋白质似乎是维持红细胞骨架蛋白正常物理功能所必需的。
