title: Bifunctional CD22 ligands use multimeric immunoglobulins as protein scaffolds in assembly of immune complexes on B cells.
abstract: 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 alpha2-6Gal. 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.
authors.affiliation: Department of Chemical Physiology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, USA.
authors.forename: Mary K
authors.initials: MK
authors.lastname: O'Reilly
authors.forename: Brian E
authors.initials: BE
authors.lastname: Collins
authors.forename: Shoufa
authors.initials: S
authors.lastname: Han
authors.forename: Liang
authors.initials: L
authors.lastname: Liao
authors.forename: Cory
authors.initials: C
authors.lastname: Rillahan
authors.forename: Pavel I
authors.initials: PI
authors.lastname: Kitov
authors.forename: David R
authors.initials: DR
authors.lastname: Bundle
authors.forename: James C
authors.initials: JC
authors.lastname: Paulson
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000936:Antigen-Antibody Complex / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D007070:Immunoglobulin A / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D007075:Immunoglobulin M / Q000276:immunology*; D008024:Ligands; D051379:Mice; D009596:Nitrophenols / Q000276:immunology; D009844:Oligosaccharides / Q000276:immunology*; D051918:Sialic Acid Binding Ig-like Lectin 2 / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D008024:Ligands; D009596:Nitrophenols; D009844:Oligosaccharides; D051918:Sialic Acid Binding Ig-like Lectin 2; C062923:N-acetylneuraminosyl(alpha2-6)lactosamine