Sinha S K, Todd S C, Hedrick J A, Speiser C L, Lambris J D, Tsoukas C D
Department of Biology, San Diego State University, CA 92182.
J Immunol. 1993 Jun 15;150(12):5311-20.
EBV is a human herpes virus that causes mononucleosis and is associated with various tumors. EBV infects cells via the CR2 that was previously thought to be expressed only on the surface of B cells and certain epithelial cells. Recent findings in our laboratory and those of others, however, have shown that the EBV receptor is also present on T cells. Our study shows that Jurkat human T cells have a molecule that reacts with both anti-CR2 antibodies and the third component of complement, C3. Furthermore, the data indicate that this molecule binds EBV detected by incubation with biotin-conjugated virus and streptavidin phycoerythrin. Viral binding is specific, as it is inhibited by nonconjugated virus, with anti-CR2 antibodies, and with an antibody reactive with the glycoprotein (gp350) that EBV uses to bind CR2. In addition, EBV variably infects Jurkat cells as demonstrated by the presence of transcripts of Epstein Barr nuclear Ag (EBNA-1) using the polymerase chain reaction. Immunoprecipitation experiments with anti-CR2 antibodies and SDS-PAGE analysis reveal a protein with an apparent molecular mass of 155 kDa which is higher than the one seen in B cells. The size of this molecule is reduced to 119 kDa upon endoglycosidase F treatment. Northern blot analysis of Jurkat poly(A)+ RNA shows a transcript of 4.7 kb upon probing with the B cell CR2 cDNA. This size is consistent with that of B cell CR2 mRNA. Two cDNA clones were identified upon screening of a Jurkat cell cDNA library with the B cell CR2 cDNA. One of the clones possesses an identical nucleotide sequence to the one corresponding to B cell CR2, whereas the other represents a differentially spliced transcript which lacks the exon 8b of B cell CR2. Analysis of Jurkat and Raji mRNA by PCR demonstrated the presence of this novel splice variant in both cell lines.
EB病毒是一种人类疱疹病毒，可引起单核细胞增多症，并与多种肿瘤相关。EB病毒通过CR2感染细胞，此前认为CR2仅在B细胞和某些上皮细胞表面表达。然而，我们实验室和其他实验室最近的研究结果表明，EB病毒受体也存在于T细胞上。我们的研究表明，Jurkat人T细胞有一种分子，它能与抗CR2抗体和补体第三成分C3发生反应。此外，数据表明，该分子能结合通过与生物素偶联病毒和链霉亲和素藻红蛋白孵育检测到的EB病毒。病毒结合具有特异性，因为它可被未偶联的病毒、抗CR2抗体以及与EB病毒用于结合CR2的糖蛋白（gp350）反应的抗体所抑制。此外，通过聚合酶链反应检测到爱泼斯坦 - 巴尔核抗原（EBNA - 1）转录本的存在，这表明EB病毒可不同程度地感染Jurkat细胞。用抗CR2抗体进行免疫沉淀实验和SDS - PAGE分析显示，有一种表观分子量为155 kDa的蛋白质，该分子量高于在B细胞中所见的蛋白质。用内切糖苷酶F处理后，该分子的大小降至119 kDa。用B细胞CR2 cDNA探针检测Jurkat多聚腺苷酸加尾（poly(A)+）RNA的Northern印迹分析显示有一条4.7 kb的转录本。这个大小与B细胞CR2 mRNA的大小一致。用B细胞CR2 cDNA筛选Jurkat细胞cDNA文库时鉴定出两个cDNA克隆。其中一个克隆具有与B细胞CR2对应的相同核苷酸序列，而另一个代表一个差异剪接的转录本，它缺少B细胞CR2的外显子8b。通过PCR分析Jurkat和Raji mRNA表明，这两种细胞系中都存在这种新的剪接变体。
