Wymann Sandra, Ghielmetti Marco, Schaub Alexander, Baumann Michael J, Stadler Beda M, Bolli Reinhard, Miescher Sylvia M
Institute of Immunology, Sahlihaus 2, Inselspital, Bern CH-3010, Switzerland.
Mol Immunol. 2008 May;45(9):2621-8. doi: 10.1016/j.molimm.2007.12.020. Epub 2008 Feb 15.
Intravenous immunoglobulin (IVIg) preparations are derived from pooled plasma from up to 60,000 healthy human donors and reflect the immunologic experience of the donor population. IVIg contains monomeric and dimeric IgG populations which are in a dynamic equilibrium depending on concentration, pH, temperature, donor pool size, time and stabilizers added in order to keep the portion of dimeric IgG below a certain level. In the present study, monomeric and dimeric fractions were isolated by size exclusion chromatography. The dimeric fractions, however, showed a dynamic instability and tended to dissociate. Both dimeric and monomeric IgG fractions were acid treated (pH 4) in order to dissociate the dimeric IgG. Western-blot analysis identified a sub-population of SDS resistant IgG dimers. Furthermore, the reactivities of the fractions were tested against a panel of self- and exo-antigens. There was a marked increase in activity of the dimeric compared to the monomeric IgG fraction against various intracellular self-antigens. Our data indicates that the increased reactivities of pH 4-treated fractions can mainly be attributed to dimer dissociation, as pH 4-treated monomers do not show significantly increased activities against a range of antigens.
静脉注射免疫球蛋白（IVIg）制剂源自多达60,000名健康人类供体的混合血浆，反映了供体群体的免疫经历。IVIg包含单体和二聚体IgG群体，它们处于动态平衡状态，这种平衡取决于浓度、pH值、温度、供体库大小、时间以及为使二聚体IgG比例保持在一定水平以下而添加的稳定剂。在本研究中，通过尺寸排阻色谱法分离出单体和二聚体组分。然而，二聚体组分表现出动态不稳定性并倾向于解离。对二聚体和单体IgG组分均进行了酸处理（pH 4）以解离二聚体IgG。蛋白质免疫印迹分析鉴定出一组耐SDS的IgG二聚体亚群。此外，还针对一组自身抗原和外源性抗原测试了这些组分的反应性。与单体IgG组分相比，二聚体针对各种细胞内自身抗原的活性有显著增加。我们的数据表明，pH 4处理组分反应性的增加主要可归因于二聚体解离，因为pH 4处理的单体针对一系列抗原并未表现出显著增加的活性。
