Supramolecular complexing of membane Siglec CD22 mediated by a polyvalent heterobifunctional ligand that templates on IgM

Abstract

We report the synthesis and in vitro evaluation of a multivalent homing device, a polymer which contains preordered pendant groups with dual specificity, a trisaccharide moiety, which is specific for the siglec CD22, and an antibody specific hapten, nitrophenol. The device efficiently attracts antihapten IgM to the surface of human lymphoma B cells as well as to CD22-conjugated magnetic beads by mediating the formation of a ternary complex on the surface of the target.

Figure 1

Assembly of immune complex of IgM and CD22 mediated by a polyvalent heterobifunctional ligand.

Figure 2

Structures of polyvalent heterobifunctional ligand 1, its unimeric control ligand 2, and its polyvalent LacNAc control ligand 3.

Figure 3

Binding of anti-NP IgM to CD22 on BJAB cells. Formation of IgM-CD22 complex was assessed by incubating BJAB cells with ligands at various concentrations and FITC labeled anti-NP IgM at 10 μg/mL, staining with FITC-anti-IgM, and measuring cell flurorescence by flow cytometry. (a) Histograms of cells treated with polyvalent ligand 1 (left) and unimeric ligand 2 (right). (b) Comparison of mean channel fluorescence (MCF) of cell samples treated with 1 and 2 at various concentrations.

Figure 4

Avidity of complex formation mediated by ligand 1 and 3 was analyzed by titrating ligands in the presence of CD22 immobilized on magnetic beads and FITC labeled anti-NP IgM (5 μg/mL), and measuring bead fluorescence by flow cytometry. Mean channel fluorescence (MCF) is plotted against ligand concentration.

Scheme 1

Synthesis of polyvalent heterobifunctional ligand 1.