and denatured protein substrates

An understanding of the binding specfficity of leukocyte integrins is important to determine the range of ligands that interact with these receptors during inflammatory processes. In this study we show that the a4131integrin can interact with casein and denatured albumin and promote leukocyte adhesion through these interactions. This was demonstrated with the use of blocking antibodies directed to a4�3j and peptide adhesion competitors containing the a43i binding tripeptide, Leu-Asp-Val (LDV). Consistent with this data, the adhesion is completely divalent cation- dependent and is stimulated by known activators of leukocyte integrin function, namely phorbol ester and theintegrm activating antibody, 8A2. It is inter- esting to note that neither bovine a-casein or human albumin contain an LDV site (present in the CS-i site of alternatively spliced fibronectin) or an IDS site (pres- ent in VCAM-1) yet they promote adhesion through