Bifunctional CD22 Ligands use multimeric immunoglobulins as protein scaffolds in assembly of immune complexes on B cells
Bifunctional CD22 Ligands use multimeric immunoglobulins as protein scaffolds in assembly of immune complexes on B cells
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DOI：
10.1021/ja802008q
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发表时间：
2008-06-18
影响因子：
15
通讯作者：
Paulson, James C.
中科院分区：
文献类型：
--
作者：
O'Reilly, Mary K.;Collins, Brian E.;Paulson, James C.
CD22是一种B细胞特异性唾液酸结合免疫球蛋白样凝集素（Siglec），其作为B细胞信号传导的调节剂的功能通过其与带有NeuAc α 2-6Gal序列的聚糖配体的相互作用而调节。迄今为止，只有高多价聚合物配体（n = 450）具有足够的亲和力，可以在天然B细胞上与CD22结合。在这里，我们证明了一种合成的双功能分子，包括CD22配体与抗原（硝基酚；NP）连接，可以使用单克隆抗NP IgM作为十价蛋白支架，有效地驱动IgM-CD22复合物在天然B细胞表面的组装。令人惊讶的是，较低效价的抗np抗体IgA （n = 4）和IgG （n = 2）也被发现可以驱动复合物的形成，尽管其活跃度较低。构建了具有可变长度和结构的替代连接体的配体，以确定最小长度要求的重要性，以及结构要求的通用性。我们发现配体只在B细胞表面驱动IgM复合物的组装，而不是在其他不表达CD22的白细胞表面，这使得它有可能在某些造血恶性肿瘤中靶向B细胞。
CD22 is a B cell-specific sialic acid-binding immunoglobulin-like lectin (Siglec) whose function as a regulator of B cell signaling is modulated by its interaction with glycan ligands bearing the sequence NeuAc alpha 2-6Gal. To date, only highly multivalent polymeric ligands (n = 450) have achieved sufficient avidity,to bind to CD22 on native B cells. Here we demonstrate that a synthetic bifunctional molecule comprising a ligand of CD22 linked to an antigen (nitrophenol; NP) can use a monoclonal anti-NP IgM as a decavalent protein scaffold to efficiently drive assembly of IgM-CD22 complexes on the surface of native B cells. Surprisingly, anti-NP antibodies of lower valency, IgA (n = 4) and IgG (n = 2), were also found to drive complex formation, though with lower avidity. Ligands bearing alternate linkers of variable length and structure were constructed to establish the importance of a minimal length requirement, and versatility in the structural requirement. We show that the ligand drives assembly of IgM complexes exclusively on the surface of B cells and not other classes of white blood cells that do not express CD22, which lends itself to the possibility of targeting B cells in certain hematopoietic malignancies.