de Préval C, Mach B
Immunogenetics. 1983;17(2):133-40. doi: 10.1007/BF00364753.
The Daudi cell line is characterized by an absence of HLA antigen on its surface. This has been attributed to a lack of beta 2-microglobulin (beta 2m) while the heavy chain of HLA is present intracellularly. Karyotype analysis of Daudi cells has shown a deletion involving one of the beta 2-microglobulin alleles. It was generally believed that the absence of beta 2-microglobulin in that cell line resulted from an absence of expression of the remaining gene. We report here the unexpected finding of a normal amount of beta 2-microglobulin messenger RNA in Daudi cells. This was demonstrated by "Northern blot" hybridization with cDNA plasmid clones as a probe. This mRNA, however, when purified by hybridization-selection with beta 2-microglobulin plasmid DNA, is unable to function as messenger in protein synthesis and is therefore an inactive mRNA. The finding of a translationally inactive beta 2-microglobulin mRNA provides a new explanation for the absence of beta 2-microglobulin and therefore of HLA antigens in Daudi cells.
Daudi细胞系的特征是其表面缺乏HLA抗原。这被认为是由于缺乏β2-微球蛋白（β2m），而HLA重链存在于细胞内。对Daudi细胞的核型分析显示涉及β2-微球蛋白等位基因之一的缺失。一般认为该细胞系中β2-微球蛋白的缺失是由于剩余基因不表达所致。我们在此报告一个意外发现，即Daudi细胞中β2-微球蛋白信使RNA的量正常。这通过用cDNA质粒克隆作为探针的“Northern印迹”杂交得以证明。然而，这种mRNA在用β2-微球蛋白质粒DNA进行杂交选择纯化后，无法在蛋白质合成中作为信使发挥作用，因此是一种无活性的mRNA。翻译无活性的β2-微球蛋白mRNA的发现为Daudi细胞中β2-微球蛋白以及因此HLA抗原的缺失提供了新的解释。
