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     Gel: 10%SDS-PAGE, Lysate: 40 μg, Lane: OP9 cells, Primary antibody: P08426(ICAM4 Antibody) at dilution 1/500, Secondary antibody: Goat anti rabbit IgG at 1/8000 dilution, Exposure time: 30 seconds    

  
  

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     The image is immunohistochemistry of paraffin-embedded Human liver cancer tissue using P08426(ICAM4 Antibody) at dilution 1/50. (Original magnification: ×200)    

  
  

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     The image is immunohistochemistry of paraffin-embedded Human brain  tissue using P08426(ICAM4 Antibody) at dilution 1/50. (Original magnification: ×200)    

  
  

ICAM4 (Intercellular Adhesion Molecule 4), also known as the Landsteiner-Wiener (LW) blood group antigen, is a cell surface glycoprotein belonging to the immunoglobulin superfamily. Primarily expressed on erythrocytes (red blood cells), it plays a role in cell-cell adhesion and signaling. Discovered through studies on blood group antigens, ICAM4 interacts with integrins on endothelial cells and leukocytes, potentially mediating erythrocyte adhesion in circulation or during inflammatory responses. Its gene, *ICAM4*, is located on chromosome 19 and encodes a protein with two extracellular immunoglobulin-like domains.

ICAM4 antibodies are clinically significant in transfusion medicine. Naturally occurring anti-LW antibodies (targeting ICAM4) can cause hemolytic transfusion reactions or hemolytic disease of the fetus/newborn (HDFN), though such cases are rare. These antibodies may arise spontaneously or after exposure to incompatible blood, particularly in individuals with LW antigen variants. In research, ICAM4 antibodies are used to study erythrocyte biology, including erythropoiesis, sickle cell disease, and malaria pathogenesis, as ICAM4 has been implicated in Plasmodium falciparum-infected red cell interactions. Monoclonal antibodies against ICAM4 also serve as tools for blood typing and investigating adhesion mechanisms in hematologic disorders.