Xu Wei, Zhu Mei, Wang Bao-Long, Su Hong, Wang Min
Department of Laboratory Medicine, Affiliated Provincial Hospital of Anhui Medical University, Hefei, Anhui, China ; Department of Blood Transfusion, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China.
Department of Nuclear Medicine, The Third Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China.
Transfus Med Hemother. 2015 Jan;42(1):15-21. doi: 10.1159/000370217. Epub 2014 Dec 22.
The D antigen is highly immunogenic, requiring only a small quantity of transfused red blood cells (RBCs) to cause alloimmunization in D- immunocompetent recipients. DEL was reported arousing alloimmunization to true Rh- patients. Molecular studies of the RHD gene have revealed that DEL individuals retain a grossly intact RHD gene or have a portion of RHD in their genomes. Avoiding immunization with clinically important antibodies is a primary objective in transfusion medicine.
In order to determine whether pregnant DEL women carrying an RhD+ fetus are at risk of anti-D alloimmunization, 808 Rh- pregnant women with a history of gestations or parturitions who regularly visited hospitals for their prenatal anti-D screening and postpartum care from January 2011 to December 2012 were investigated. Samples were analyzed for DEL by PCR with specific primers, PCR-sequence-specific primers (PCR-SSP), reverse transcription-PCR (RT-PCR), PCRrestriction fragment length polymorphism (PCR-RFLP), and by gene sequencing to characterize different alleles.
Among the 808 Rh- pregnant women of our sample, 178 (22.0%) were typed as DEL; 168 DEL samples were confirmed to have the RHD (1,227 G>A) allele, 8 DEL samples were characterized by one base mutation of the RHD (3G >A) allele, and the remaining two DEL samples were determined to carry RHD-CE(4-9)-D or RHD-CE(2-5)-D. The observation of allo-anti-D in two prominent D epitope loss cases confirmed the partial nature of these DEL phenotypes.
In conclusion, evidence is provided that different DEL genotypes code either for partial or complete D antigen expression. It is suggested that the use of RhD+ RBCs in complete D antigen DEL patients does not induce adverse reaction.
D抗原具有高度免疫原性，仅需少量输注的红细胞（RBC）即可在具有D免疫活性的受者中引起同种免疫。据报道，DEL会引起真正的Rh阴性患者发生同种免疫。对RHD基因的分子研究表明，DEL个体的RHD基因大体上保持完整，或者其基因组中含有一部分RHD基因。避免产生具有临床重要性的抗体是输血医学的主要目标。
为了确定怀有RhD阳性胎儿的DEL孕妇是否有发生抗-D同种免疫的风险，对2011年1月至2012年12月期间定期到医院进行产前抗-D筛查和产后护理、有妊娠或分娩史的808名Rh阴性孕妇进行了调查。采用特异性引物PCR、PCR-序列特异性引物（PCR-SSP）、逆转录PCR（RT-PCR）、PCR-限制性片段长度多态性（PCR-RFLP）以及基因测序对样本进行DEL分析，以鉴定不同的等位基因。
在我们样本中的808名Rh阴性孕妇中，178名（22.0%）被鉴定为DEL；168份DEL样本被证实具有RHD（1227G>A）等位基因，8份DEL样本的特征是RHD（3G>A）等位基因发生一个碱基突变，其余两份DEL样本被确定携带RHD-CE(4-9)-D或RHD-CE(2-5)-D。在两例明显的D抗原表位缺失病例中观察到同种抗-D，证实了这些DEL表型的部分性质。
总之，有证据表明不同的DEL基因型编码部分或完全D抗原表达。建议在完全D抗原DEL患者中使用RhD阳性RBC不会引起不良反应。
