新生儿成熟度对免疫球蛋白重链可变区基因重排多样性的影响

The effect of neonatal maturity on diversity of immunoglobulin heavy variable region gene

目的 :分析不同胎龄新生儿免疫球蛋白重链可变区 (IgH)基因序列特征 ,探讨新生儿成熟度对其多样性的影响。方法 :10例极不成熟儿、12例不成熟儿和 11例成熟儿的脐血淋巴细胞DNA被抽提 ,IgH基因被扩增、克隆和测序。结果 :极不成熟儿和不成熟儿优先使用VH1和VH3 ,成熟儿的VH3使用率下降 ;所有新生儿中 ,JH3和JH6使用率较高。极不成熟儿、不成熟儿和成熟儿的NDN长度分别为 ( 13 5± 7 2 )、( 16 8± 6 5)和 ( 2 2 3± 7 2 )bp ,体突变率分别为 15 8%、2 3 6%和2 9 5% ,均为点突变。极不成熟儿、不成熟儿和成熟儿中 ,分别 78 3%、84 7%和 92 4 %的克隆有开放性阅读框。结论 :新生儿的VH-D -JH 重排机制已处于活化状态但多样性有限 ,不同成熟度新生儿的IgH基因存在异型性 ,表明体液免疫系统的发育是一个渐进的过程。

Aim:To study the effect of neonatal maturity on diversity of immunoglobulin heavy variable region (IgH) gene. Methods:DNA were extracted from cord blood of 10 very immature, 12 immature and 11 mature neonates, IgH gene was amplified using nested PCR technique, then cloned and sequenced. Results: V H1 is preferentially used in very immature and immature neonates, V H3 in mature neonates, and the usage of J H3 is highest in all neonates. There are an NDN length of (13.5±7.2), (17.8±7.5) and (23.3±8.2) bp, a somatic mutation (point mutation) rate of 15.8%, 23.6% and 29.5%, and an open reading frame of 78.3%、84.7% and 92.4% in very immature,immature and mature neonates, respectively. Conclusion:During the early life of neonates, V H-D-J H rearrangement of IgH gene is in an activated condition. Heterogeneity of IgH gene exists in neonates with different maturity, and humoral immunity is a step by step development with increasing maturity in neonates.[