Gasque P, Chan P, Mauger C, Schouft M T, Singhrao S, Dierich M P, Morgan B P, Fontaine M
Deptment of Medical Biochemistry, University of Wales College of Medicine, Cardiff, United Kingdom.
J Immunol. 1996 Mar 15;156(6):2247-55.
Astrocytes express C components and have been implicated as a major source of intrathecal C. To ascertain the effects of C activation on these cells, we have evaluated the expression of CR1, CR2, and CR3 (CD35, CD21, and CD11b/CD18) in primary fetal astrocytes and astrocyte cell lines. None of the astrocyte cells tested expressed CR3, whereas primary astrocytes and one of four astrocyte cell lines expressed CR1 (220 kDa), as assessed at the protein and mRNA level. Primary fetal astrocytes and all four astrocyte cell lines expressed CR2 (155 kDa). Expression of CR2 by astrocytes was confirmed at mRNA level by reverse-transcriptase PCR, using different combinations of seven specific CR2 oligonucleotides, and by partial sequencing of the astrocyte CR2 cDNA. Astrocyte CR2 cDNA presented 100% homology with the lymphocyte CR2 cDNA between the position 181 bp to 600 bp and position 1017 bp to 1347 bp. An alternative splicing pattern of exon 11, reported previously in B cells, was observed in astrocyte CR2 cDNA. Astrocyte CR2 was functional, in that it specifically bound C3d and the EBV surface protein gp340, and the binding was blocked specifically with polyclonal anti-CR2. Scatchard analysis of membrane expression of CR2 on astrocytes revealed 2000 functional sites per cell with a Kd (3 x 10(-7) M) identical with that of CR2 on B cell (Raji).
星形胶质细胞表达补体C成分，并且被认为是鞘内补体C的主要来源。为了确定补体C激活对这些细胞的影响，我们评估了原代胎儿星形胶质细胞和星形胶质细胞系中CR1、CR2和CR3（CD35、CD21和CD11b/CD18）的表达。所检测的星形胶质细胞均未表达CR3，而原代星形胶质细胞和四个星形胶质细胞系中的一个表达CR1（220 kDa），这是在蛋白质和mRNA水平评估得出的结果。原代胎儿星形胶质细胞和所有四个星形胶质细胞系均表达CR2（155 kDa）。通过逆转录聚合酶链反应（reverse-transcriptase PCR），使用七种特异性CR2寡核苷酸的不同组合，并通过对星形胶质细胞CR2 cDNA进行部分测序，在mRNA水平证实了星形胶质细胞对CR2的表达。星形胶质细胞CR2 cDNA在181 bp至600 bp以及1017 bp至1347 bp位置与淋巴细胞CR2 cDNA呈现100%同源性。在星形胶质细胞CR2 cDNA中观察到了先前在B细胞中报道的外显子11的可变剪接模式。星形胶质细胞CR2具有功能，因为它特异性结合C3d和EB病毒表面蛋白gp340，并且这种结合可被多克隆抗CR2特异性阻断。对星形胶质细胞上CR2的膜表达进行Scatchard分析显示，每个细胞有2000个功能位点，其解离常数（Kd，3×10⁻⁷ M）与B细胞（Raji细胞）上的CR2相同。
