Clonal populations of hematopoietic cells with paroxysmal nocturnal hemoglobinuria genotype and phenotype are present in normal individuals
Clonal populations of hematopoietic cells with paroxysmal nocturnal hemoglobinuria genotype and phenotype are present in normal individuals
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DOI：
10.1073/pnas.96.9.5209
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发表时间：
1999-04-27
影响因子：
11.1
通讯作者：
Luzzatto, L
中科院分区：
文献类型：
--
作者：
Araten, DJ;Nafa, K;Luzzatto, L
在阵发性夜间血红蛋白尿（PNH）中，猪- a基因的获得性体细胞突变导致红细胞克隆群体无法表达通过糖基磷脂酰肌醇锚点与膜连接的蛋白质。这些蛋白包括补体抑制剂CD55和CD59，这解释了PNH患者对补体红细胞的超敏反应，表现为血管内溶血。决定突变克隆扩展到何种程度的因素尚未确定；已有研究表明，现有的PNH克隆可能具有条件生长优势，这取决于PNH患者骨髓环境中存在的某些因素（例如自身免疫）。利用流式细胞术对粒细胞进行分析，我们现在已经确定了9个正常人中具有PNH表型的细胞，平均频率为百万分之22（范围为百万分之10-51）。通过流式分选收集这些罕见的细胞，通过巢式PCR扩增出猪- a基因外显子2和6，发现6例猪- a基因突变：4例错义突变，1例移码突变，1例无义突变。PNH红血球也被鉴定为百万分之八。因此，具有猪- a突变的小克隆在正常个体中普遍存在，这清楚地表明猪- a。基因突变不足以导致PNH的发生。由于猪- a基因编码一种对宿主表面蛋白表达至关重要的酶，因此猪- a基因为研究造血细胞的体细胞突变提供了一个高度敏感的系统。
In paroxysmal nocturnal hemoglobinuria (PNH), acquired somatic mutations in the PIG-A gene give rise to clonal populations of red blood cells unable to express proteins linked to the membrane by a glycosylphosphatidylinositol anchor. These proteins include the complement inhibitors CD55 and CD59, and this explains the hypersensitivity to complement of red cells in PNH patients, manifested by intravascular hemolysis. The factors that determine to what extent mutant clones expand have not yet been pinpointed; it has been suggested that existing PNH clones may have a conditional growth advantage depending on some factor (e.g., autoimmune) present in the marrow environment of PNH patients. Using flow cytometric analysis of granulocytes, we now have identified cells that have the PNH phenotype, at an average frequency of 22 per million (range 10-51 per million) in nine normal individuals. These rare cells were collected by flow sorting, and exons 2 and 6 of the PIG-A gene were amplified by nested PCR, We found PIG-A mutations in six cases: four missense, one frameshift, and one nonsense mutation. PNH red blood cells also were identified at a frequency of eight per million. Thus, small clones with PIG-A mutations exist commonly in normal individuals, showing clearly that PIG-A. gene mutations are not sufficient for the development of PNH. Because PIG-A encodes an enzyme essential for the expression of a host of surface proteins, the PIG-A gene provides a highly sensitive system for the study of somatic mutations in hematopoietic cells.