A direct binding assay for the vascular cell adhesion molecule-1 (VCAM1) interaction with alpha 4 integrins

Cell Adhes Commun. 1995 Dec;3(5):385-97. doi: 10.3109/15419069509081293.


Vascular cell adhesion molecule-1 (VCAM1) is a member of the immunoglobulin (Ig) superfamily which interacts with the alpha 4 integrins alpha 4 beta 1 (very late antigen 4: VLA4) and alpha 4 beta 7, which are constitutively expressed on many leukocyte subsets and play a key role in cell trafficking and activation. Using a recombinant VCAM-IgG fusion protein (VCAM-Ig) as a soluble ligand for alpha 4 beta 1 we directly demonstrated by fluorescence analysis that the alpha 4 beta 1 receptor can exist in different affinity states on the cell surface, and that a high affinity state is induced by manganese ions or certain activating anti-beta 1 monoclonal antibodies (Jakubowski et al., 1995b). Here we have extended these observations by developing a rapid and reproducible assay using alkaline phosphatase (AP)-coupled VCAM-Ig (VCAM-Ig-AP) which measures the interaction between VCAM1 and alpha 4 integrins in a microtiter plate format. This assay has allowed us to evaluate directly the effects of metal ions, anti-beta 1 mAbs, and different cell types and species on the VCAM1/alpha 4 integrin interaction. Most importantly, the assay system provides a means to rapidly evaluate alpha 4 integrin-directed inhibitors without the complication of post-ligand binding events inherent in adhesion assays.

MeSH terms

  • Animals
  • Antibodies, Monoclonal / metabolism
  • Antigens, CD / metabolism*
  • Binding, Competitive / drug effects
  • Binding, Competitive / physiology
  • Cell Adhesion / physiology
  • Fluorescent Antibody Technique
  • Humans
  • Integrin alpha4
  • Integrins / metabolism*
  • Leukemia
  • Magnesium / pharmacology
  • Mice
  • Protein Binding / physiology
  • Rats
  • Tumor Cells, Cultured / chemistry
  • Tumor Cells, Cultured / cytology
  • Tumor Cells, Cultured / metabolism
  • Vascular Cell Adhesion Molecule-1 / immunology
  • Vascular Cell Adhesion Molecule-1 / metabolism*


  • Antibodies, Monoclonal
  • Antigens, CD
  • Integrins
  • Vascular Cell Adhesion Molecule-1
  • Integrin alpha4
  • Magnesium