The long range goal of this project is to understand mechanisms of cellular immune reactions in the central nervous system (CNS). The overall hypothesis is that surface expression of specific molecules on inflammatory and CNS resident cells play critical roles in immune- mediated injury. CNS tissue samples from animals with experimental allergic encephalomyelitis (EAE), a model of multiple sclerosis (MS), and from patients with CNS diseases are studied using routine histology and immunohistochemistry at the light microscopic and ultrastructural levels to visualize directly the locations of cell surface molecules that are effectors and targets in CNS immune reactions. The studies to be performed in the proposed grant period will determine: 1. (A) The regions of myelin proteolipid protein (PLP) that are localized on the external surface (intermediate dense line) and those epitopes that are localized on the cytoplasmic face (major dense line) in compact CNS myelin and (B) whether antibodies with specificities to epitopes on the external surface induce more demyelination than antibodies to epitopes on the cytoplasmic face in vivo in an acute EAE model. 2. Whether cell-surface integrin receptors of vitronectin and laminin are expressed on inflammatory cells in lesions of EAE and MS and whether this expression and colocalization with vitronectin and laminin correlate with the degree of inflammation and demyelination. 3. Whether the temporal dynamics, extent of infiltration of T cell receptor V tau delta+ cells and their target heat shock proteins correlate with clinical manifestations and type and degree of histologic injury in a mouse model of chronic EAE. This research addresses both the normal molecular structure of CNS myelin and mechanisms of demyelination in MS and other demyelinating diseases. Because integrins are both used by neoplastic cells for tissue invasion and by microorganisms as receptors, the results will also have implications for the pathogenesis of CNS metastatic tumors and infections.