Accumulating evidence suggests that defects in alveolar macrophage function may contribute to the observed pulmonary opportunistic infections in HIV-1 infected individuals. This grantee will examine the role of fibronectin receptors in controlling the adherence and motile properties of alveolar macrophages. After identifying fibronectin receptors (integrins) on lung macrophages that bind to fibronectin, the investigators plan to use a mathematical model to guide them in examining the role of receptor-ligand (fibronectin) interactions in regulating the adhesive strength of alveolar macrophages. The role of this interaction in regulating the motile behavior of macrophages will then be determined. Finally the investigators will employ video microscopy and image analysis to test their hypotheses regarding relationships between cell speed and fibronectin density. Understanding these interactions could have broad applicability to other receptor ligand interactions and could provide important understanding of the interaction between cell surface receptors and ligands bound to structures in the extracellular matrix.