Daniels G L, Green C A, Mallinson G, Okubo Y, Hori Y, Kataoka A, Kaihara M
Bristol Institute for Transfusion Sciences, UK.
Transfus Med. 1998 Jun;8(2):141-7. doi: 10.1046/j.1365-3148.1998.00145.x.
Decay-accelerating factor (DAF, CD55) is a complement regulatory glycoprotein that expresses the Cromer-system blood group antigens. Two, very rare, inherited DAF-deficiency phenotypes, Inab and Dr(a-), were identified in Japanese propositi. Red cells of the Inab phenotype propositus had no Cromer-system antigens and did not bind monoclonal anti-DAF. The Inab propositus was homozygous for a DAF non-sense mutation, converting the Trp53 codon to a stop codon; her parents were heterozygous for this mutation. This is the same mutation as that previously found in the original Inab phenotype propositus. Haemagglutination-inhibition titrations of the serum of the Inab propositus with soluble-recombinant DAF demonstrated that anti-IFC represents a mixture of antibodies to all four DAF short consensus repeat domains. The Dr(a-) individual had very low levels of Cromer-system antigens and DAF on her red cells. Loss of a TaqI restriction site from DAF exon 5 suggested that she has a previously detected mutation, encoding a Ser165Leu substitution. Red cells of the two propositi did not show abnormal levels of lysis in an acid lysis test, but after blocking of CD59 with monoclonal antibody, Inab phenotype red cells showed more lysis than Dr(a-) red cells, and Dr(a-) cells showed substantially more lysis than control cells.
衰变加速因子（DAF，CD55）是一种表达克罗马系统血型抗原的补体调节糖蛋白。在日本的先证者中鉴定出两种非常罕见的遗传性DAF缺陷表型，即Inab和Dr(a-)。Inab表型先证者的红细胞没有克罗马系统抗原，也不结合单克隆抗DAF。Inab先证者是DAF无义突变的纯合子，将Trp53密码子转换为终止密码子；她的父母是该突变的杂合子。这与先前在原始Inab表型先证者中发现的突变相同。用可溶性重组DAF对Inab先证者血清进行血凝抑制滴定表明，抗IFC代表针对所有四个DAF短共有重复结构域的抗体混合物。Dr(a-)个体的红细胞上克罗马系统抗原和DAF水平非常低。DAF外显子5的TaqI限制性位点缺失表明她有先前检测到的突变，编码Ser165Leu替代。两名先证者的红细胞在酸溶解试验中未显示异常水平的溶解，但在用单克隆抗体阻断CD59后，Inab表型红细胞比Dr(a-)红细胞显示出更多的溶解，而Dr(a-)细胞比对照细胞显示出更多的溶解。
