A diabody that dissociates to monomer forms at low concentration: effects on binding activity and tumor targeting.
A human scFv, 15-9, was selected from a phage display library for binding to murine laminin-1. A diabody was made from the scFv by shortening the linker from 15 to 5 amino acids between the VH and VL sequence. Radioiodinated scFv and diabody were analyzed for size, binding to laminin, and biodistribution in tumor bearing mice. Diabody preparations at concentrations greater than 10 nM were largely dimer forms (approximately 60 kDa) as judged by gel filtration, but diluted diabody was eluted as a monomer (approximately 30 kDa). At low concentrations the radiolabeled diabody did not bind well to laminin. The (125)I diabody had significantly lower accumulation in tumors than did the scFv when injected at lower concentrations. These data indicate that the diabody dimer dissociates at concentrations of about 10nM resulting in monomers with no binding activity for laminin and poor tumor homing properties.
Huang
Bao-Cheng
BC
Life Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
Foote
Linda J
LJ
Lankford
Trish K
TK
Davern
Sandra M
SM
McKeown
Cathy K
CK
Kennel
Stephen J
SJ
D000818:Animals; D000915:Antibody Affinity / Q000276:immunology*; D000918:Antibody Specificity / Q000276:immunology; D002850:Chromatography, Gel; D005260:Female; D007135:Immunoglobulin Variable Region / Q000032:analysis / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*; D007457:Iodine Radioisotopes; D007797:Laminin / Q000276:immunology / Q000378:metabolism; D051379:Mice; D016513:Mice, SCID; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000276:immunology*; D015202:Protein Engineering; D021122:Protein Subunits / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000493:pharmacokinetics; D014018:Tissue Distribution
D007135:Immunoglobulin Variable Region; D007457:Iodine Radioisotopes; D007797:Laminin; D021122:Protein Subunits; C121346:laminin 1