Mutations of the CD40 ligand gene and its effect on CD40 ligand expression in patients with X-linked hyper IgM syndrome.
Mutations of the CD40 ligand gene and its effect on CD40 ligand expression in patients with X-linked hyper IgM syndrome.
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DOI：
10.1182/blood.v92.7.2421.2421_2421_2434
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发表时间：
1998-10
期刊：
影响因子：
20.3
通讯作者：
K. Seyama;S. Nonoyama;Ingvild Gangsaas;D. Hollenbaugh;H. Pabst;A. Aruffo;H. Ochs
中科院分区：
文献类型：
--
作者：
K. Seyama;S. Nonoyama;Ingvild Gangsaas;D. Hollenbaugh;H. Pabst;A. Aruffo;H. Ochs
x连锁高IgM综合征（XHIM）是一种由编码CD40配体（CD40L）的基因突变引起的原发性免疫缺陷疾病。我们将来自30个家族的XHIM患者的CD40L基因突变、CD40L表达与临床表现相关联。鉴定的28个独特突变包括9个错义突变，5个无义突变，9个剪接位点突变和5个缺失/插入。在9个剪接位点突变中，有4个正常剪接和突变的mRNA转录本同时表达。RNase保护实验表明，17个突变中有5个导致转录物水平下降。利用一种多克隆抗体和四种单克隆抗体以及一种CD40-Ig融合蛋白，评估突变对活化的外周血单核细胞（PBMC）和t细胞系或克隆表达CD40L的影响。在大多数患者中，观察到至少有一种抗体结合，而不是CD40-Ig，提示CD40L无功能。然而，来自三名患者的PBMC和来自另外两名不同基因型患者的t细胞系被激活，以低强度结合CD40-Ig，表明CD40L具有功能。因此，活化的PBMC不能结合CD40-Ig并不是XHIM的绝对诊断标志，正确的诊断可能需要CD40L基因的分子分析。基因型导致野生型CD40L表达减少或仍能结合CD40-Ig的突变型CD40L的患者似乎具有较轻的临床后果。
X-linked hyper IgM syndrome (XHIM) is a primary immunodeficiency disorder caused by mutations of the gene encoding CD40 ligand (CD40L). We correlated mutations of the CD40L gene, CD40L expression, and the clinical manifestations observed in XHIM patients from 30 families. The 28 unique mutations identified included 9 missense, 5 nonsense, 9 splice site mutations, and 5 deletions/insertions. In 4 of 9 splice site mutations, normally spliced and mutated mRNA transcripts were simultaneously expressed. RNase protection assay demonstrated that 5 of 17 mutations tested resulted in decreased levels of transcript. The effect of the mutations on CD40L expression by activated peripheral blood mononuclear cells (PBMC) and T-cell lines or clones was assessed using one polyclonal and four monoclonal antibodies and a CD40-Ig fusion protein. In most patients, the binding of at least one antibody but not of CD40-Ig was observed, suggesting nonfunctional CD40L. However, activated PBMC from three patients and activated T-cell lines from two additional patients, each with different genotype, bound CD40-Ig at low intensity, suggesting functional CD40L. Thus, failure of activated PBMC to bind CD40-Ig is not an absolute diagnostic hallmark of XHIM and molecular analysis of the CD40L gene may be required for the correct diagnosis. Patients with genotypes resulting in diminished expression of wild-type CD40L or mutant CD40L that can still bind CD40-Ig appear to have milder clinical consequences.