Humanized porcine VCAM-specific monoclonal antibodies with chimeric IgG2/G4 constant regions block human leukocyte binding to porcine endothelial cells

Mol Immunol. 1997 Apr;34(6):441-52. doi: 10.1016/s0161-5890(97)00042-4.


Discordant xenografts surviving the initial hyperacute rejection phase may be subject to cellular rejection processes mediated by infiltrating leukocytes including T cells, NK cells and monocytes. The stable adhesion of these cell types to endothelial cells is due to the molecular interaction of the integrins VLA-4 and LFA-1 with their ligands vascular cell adhesion molecule (VCAM) and ICAM-1 present on the endothelial cells. Human VLA-4 binds to porcine VCAM, and blocking mAbs specific for porcine VCAM have been developed. We have localized the epitope of the anti-porcine VCAM blocking mAbs 2A2 and 3F4 to domains 1 and 2, respectively. Humanized antibodies (IgG4 isotype) were constructed from these anti-porcine VCAM antibodies and demonstrated to inhibit adhesion of Ramos, Jurkat and YT cells, as well as purified resting and activated human T cells, to porcine aortic endothelial cells (PAEC). These cell types express both LFA-1 as well as VLA-4, suggesting blockade of human VLA-4 interaction with porcine VCAM may alone be sufficient to significantly impair adhesion of human leukocytes to porcine endothelial cells. The chimeric anti-porcine VCAM (pVCAM) HuG4 antibodies promoted increased adhesion of Fc receptor (FcR) positive cells such as U937 monocytic cells to PAEC. In contrast, chimeric anti-porcine VCAM antibodies created using the CH1 and hinge region from human IgG2 and the CH2 and CH3 regions from human IgG4 (HuG2/G4 antibodies) inhibited binding of FcR positive cells to PAEC. These chimeric anti-pVCAM antibodies should allow delineation of the in vivo role of VLA-4/VCAM interaction in porcine-to-primate xenotransplants. Further, the design of the HuG2/G4 antibodies should render them efficacious in multiple settings requiring elimination of FcR binding.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies, Monoclonal / immunology
  • Binding, Competitive
  • Cell Adhesion*
  • Cell Line
  • Endothelium, Vascular / cytology*
  • Epitope Mapping
  • Humans
  • Immunoglobulin G / chemistry
  • Leukocytes / cytology*
  • Molecular Sequence Data
  • Receptors, Fc / metabolism
  • Recombinant Fusion Proteins
  • Swine
  • Vascular Cell Adhesion Molecule-1 / immunology


  • Antibodies, Monoclonal
  • Immunoglobulin G
  • Receptors, Fc
  • Recombinant Fusion Proteins
  • Vascular Cell Adhesion Molecule-1

Associated data

  • GENBANK/U78799
  • GENBANK/U78800
  • GENBANK/U78801
  • GENBANK/U78802