NONRANDOM X-CHROMOSOME INACTIVATION IN B-CELLS FROM CARRIERS OF X-CHROMOSOME-LINKED SEVERE COMBINED IMMUNODEFICIENCY
NONRANDOM X-CHROMOSOME INACTIVATION IN B-CELLS FROM CARRIERS OF X-CHROMOSOME-LINKED SEVERE COMBINED IMMUNODEFICIENCY
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DOI：
10.1073/pnas.85.9.3090
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发表时间：
1988-05-01
影响因子：
11.1
通讯作者：
PUCK, JM
中科院分区：
文献类型：
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作者：
CONLEY, ME;LAVOIE, A;PUCK, JM
X染色体连锁的严重联合免疫缺陷（XSCID）的特征是T细胞数量显著减少、缺乏对有丝分裂原的增殖反应和低丙种球蛋白血症，但B细胞数量正常或升高。为了确定B细胞产生免疫球蛋白的失败是否可能是由于B系细胞以及T细胞中XSCID基因缺陷的表达，我们分析了来自该疾病的9个专性携带者的B细胞中X染色体失活的模式。一系列选择性保留活性X染色体的体细胞杂种是从每个妇女的EB病毒刺激的B细胞中产生的。为了区分两个X染色体，使用X连锁限制性片段长度多态性分析每个女性的杂交体，该女性是杂合子。在所有XSCID的专性携带者中，B细胞杂交体表现出优先使用单个X染色体，即非突变X，作为活性X。为了确定含有突变X的少量B细胞杂交体是否来自未成熟的B细胞亚群，在暴露于EB病毒和产生B细胞杂交体之前，将来自三个携带者的淋巴细胞分离成表面IgM阳性和表面IgM阴性B细胞。结果表明，在来自较不成熟的表面IgM阳性B细胞的B细胞杂交体中，X染色体失活是正常的。相反，在所有三个实验中，表面IgM阴性的B细胞中的X染色体失活模式（其经历了进一步的复制和分化）是显著非随机的[比值对数（lod）得分> 3.0]。这些结果表明，XSCID基因产物对B细胞以及T细胞具有直接作用，并且在B细胞成熟期间是必需的。
X chromosome-linked severe combined immunodeficiency (XSCID) is characterized by markedly reduced numbers of T cells, the absence of proliferative responses to mitogens, and hypogammaglobulinemia but normal or elevated numbers of B cells. To determine if the failure of the B cells to produce immunoglobulin might be due to expression of the XSCID gene defect in B-lineage cells as well as T cells, we analyzed patterns of X chromosome inactivation in B cells from nine obligate carriers of this disorder. A series of somatic cell hybrids that selectively retained the active X chromosome was produced from Epstein-Barr virus-stimulated B cells from each woman. To distinguish between the two X chromosomes, the hybrids from each woman were analyzed using an X-linked restriction fragment length polymorphisms for which the woman in question was heterozygous. In all obligate carriers of XSCID, the B-cell hybrids demonstrated preferential use of a single X chromosome, the nonmutant X, as the active X. To determine if the small number of B-cell hybrids that contained the mutant X were derived from an immature subset of B cells, lymphocytes from three carriers were separated into surface IgM positive and surface IgM negative B cells prior to exposure to Epstein-Barr virus and production of B-cell hybrids. The results demonstrated normal random X chromosome inactivation in B-cell hybrids derived from the less mature surface IgM positive B cells. In contrast, the pattern of X chromosome inactivation in the surface IgM negative B cells, which had undergone further replication and differentiation, was significantly nonrandom in all three experiments [logarithm of odds (lod) score > 3.0]. These results suggest that the XSCID gene product has a direct effect on B cells as well as T cells and is required during B-cell maturation.