title: Agonistic activity of a CD40-specific single-chain Fv constructed from the variable regions of mAb G28-5.
abstract: A single-chain Fv (sFv) was expressed from the variable regions of the CD40-specific mAb G28-5. The molecule bound CD40 with a high affinity (2.2 nM) and was a monomer in solution. Surprisingly, G28-5 sFv was a potent CD40 agonist that rapidly crosslinked CD40 on the cell surface but did not crosslink CD40-Ig in solution. G28-5 sFv was a more potent agonist than G28-5 IgG and was able to stimulate CD40 responses by B cells and monocytes. G28-5 IgG partially blocked, whereas G28-5 sFv augmented CD40 responses during stimulation with natural ligand (gp39-CD8 fusion protein). These results indicate that the functional activity of ligands built from the binding site of G28-5 is highly dependent upon the size and physical properties of the molecule both in solution and on the cell surfaces.
authors.affiliation: Bristol-Myers Squibb Pharmaceutical Research Institute, Seattle, WA 98121, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Ledbetter
authors.forename: J A
authors.initials: JA
authors.lastname: Francisco
authors.forename: C B
authors.initials: CB
authors.lastname: Siegall
authors.forename: L K
authors.initials: LK
authors.lastname: Gilliland
authors.forename: D
authors.initials: D
authors.lastname: Hollenbaugh
authors.forename: A
authors.initials: A
authors.lastname: Aruffo
authors.forename: A W
authors.initials: AW
authors.lastname: Siadak
authors.forename: N
authors.initials: N
authors.lastname: Mischel-Petty
authors.forename: L S
authors.initials: LS
authors.lastname: Grosmaire
authors.forename: M L
authors.initials: ML
authors.lastname: Gordon
authors.forename: T J
authors.initials: TJ
authors.lastname: Brown
authors.forename: P
authors.initials: P
authors.lastname: Moran-Davis
authors.forename: R S
authors.initials: RS
authors.lastname: Mittler
authors.forename: P A
authors.initials: PA
authors.lastname: Kiener
authors.forename: S G
authors.initials: SG
authors.lastname: Nadler
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D019013:CD40 Antigens / Q000276:immunology*; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004727:Endothelium / Q000166:cytology; D015870:Gene Expression; D006801:Humans; D007128:Immunoglobulin Fragments / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D007135:Immunoglobulin Variable Region / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D009000:Monocytes / Q000276:immunology; D016328:NF-kappa B / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D019013:CD40 Antigens; D007128:Immunoglobulin Fragments; D007135:Immunoglobulin Variable Region; D016328:NF-kappa B; C055966:immunoglobulin Fv