A LEUKOCYTE INTEGRIN BINDING PEPTIDE FROM INTERCELLULAR-ADHESION MOLECULE-2 STIMULATES T-CELL ADHESION AND NATURAL-KILLER-CELL ACTIVITY

Adhesion is of pivotal importance for a number of leukocyte functions. Little is known about the binding between leukocyte integrins and the intercellular adhesion molecules (ICAMs). Normally integrins are nona dhesive, and require a stimulus to become active. We have now identifi ed a peptide from ICAM-2, which binds to leukocyte integrins and activ ates adhesion. Furthermore, the peptide strongly increased the binding and cytotoxicity of natural killer cells. These findings show that ad hesion-dependent leukocyte functions can be activated by ligand-derive d peptides, and therefore provide evidence that the avidity of leukocy te integrins is up-regulated by integrin-ligand interactions.