Intercellular adhesion molecule 3, a third adhesion counter-receptor for lymphocyte function-associated molecule 1 on...

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• Lymphocyte function-associated molecule 1 (LFA-1) mediates T and B lymphocyte adhesion.
• Known LFA-1 counter-receptors include intercellular adhesion molecules (ICAMs)-1 and -2.
• Some lymphocyte binding to LFA-1 occurs independently of ICAM-1 and ICAM-2.

Purpose of the Study:

• To identify novel ligands for LFA-1 on T and B lymphocytes.
• To characterize the functional role of these ligands in lymphocyte adhesion.

Main Methods:

• Generation of a monoclonal antibody (mAb) against a novel LFA-1 ligand.
• Inhibition assays using blocking mAbs against ICAM-1, ICAM-2, and the novel ligand.
• Characterization of the novel ligand's molecular weight and expression patterns.

Main Results:

• A third ICAM, designated ICAM-3, was identified as a functional ligand for LFA-1.
• ICAM-3 is a highly glycosylated protein (124,000 Mr) expressed on leukocytes but not endothelial cells.
• ICAM-3 is the primary mediator of resting lymphocyte adhesion to purified LFA-1.

Conclusions:

• ICAM-3 is a critical adhesion molecule involved in lymphocyte interactions.
• The identification of ICAM-3 provides new insights into the mechanisms of immune responses.
• Targeting ICAM-3 may offer therapeutic strategies for immune modulation.