Ellis S A, Palmer M S, McMichael A J
Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford, UK.
J Immunol. 1990 Jan 15;144(2):731-5.
Extravillous trophoblast from normal human placenta has been shown previously to express an unusual form of HLA class I molecule, as does a choriocarcinoma cell line, BeWo. This molecule has a H chain of approximately 40 kDa and appears to be nonpolymorphic. We have isolated and sequenced a HLA class I cDNA clone, which probably corresponds to this molecule, from a library derived from BeWo. The nucleotide sequence shows a high degree of homology with the published sequence of a genomic clone, HLA 6.0, which is the product of a class I locus other than A, B, or C, (provisionally designated "HLA G"). The expressed product of this locus has not previously been localized. We have used the polymerase chain reaction to demonstrate the presence of similar HLA class I sequences in cDNA from normal extravillous trophoblast. Although there is some nucleotide sequence polymorphism the amino acid sequence of this molecule is conserved. It is therefore unlikely to provoke immune responses even though it is found at the fetal-maternal interface.
先前已证明，来自正常人类胎盘的绒毛外滋养层细胞表达一种不寻常形式的HLA I类分子，绒毛膜癌细胞系BeWo也是如此。该分子具有一条约40 kDa的重链，似乎是非多态性的。我们从源自BeWo的文库中分离并测序了一个HLA I类cDNA克隆，它可能与该分子相对应。核苷酸序列与已发表的基因组克隆HLA 6.0的序列具有高度同源性，HLA 6.0是A、B或C以外的I类基因座的产物（暂定为“HLA G”）。该基因座的表达产物此前尚未定位。我们使用聚合酶链反应证明了正常绒毛外滋养层细胞的cDNA中存在类似的HLA I类序列。尽管存在一些核苷酸序列多态性，但该分子的氨基酸序列是保守的。因此，即使它存在于胎儿-母体界面，也不太可能引发免疫反应。
