Alterations in cellular immunity and in production of lymphokines (non-immunoglobulin mediators of immune responses) occur in patients with diseases ranging from cancer to occupationally- acquired allergic contact dermatitis. Clarification of the in vivo role of lymphokines and accurate quantification of them in vitro depends on biochemical characterization and production of specific antibodies as reagents for further analysis of these molecules. Macrophage agglutination factor (MAggF) is a fibronectin (FN)-related lymphokine associated with cell- mediated inflammatory reactions in guinea pigs, mice and human beings. The FNs are a family of closely related high molecular weight glycoproteins involved in cell adhesion and regulation of cell morphology with binding sites for collagen, heparin, fibrin and cells. Subproject 1 will continue further characterization of MAggF with the aim of clarifying the relationship of MAggF and FN. The specificity and activity of monoclonal anti-MAggF and anti-FN antibodies will be characterized in order to discover antibodies specific for MAggF and not cross reactive with other FNs. Biochemical and immunochemical properties of MAggF purified by gelatin affinity chromatography and immunoabsorption will be compared to those of plasma FN. In subproject 2, characterized anti-MAggF and anti-FN antibodies will be used to evaluate the role of MAggF in vivo in contact dermatitis and delayed hypersensitivity reactions, and in vitro in an antigen-bead model of cell-mediated inflammation. Subproject 3 will focus on the effects of MAggF on macrophages and the mechanisms of these effects. The role of macrophage complement receptors in the response to MAggF will be examined as will the ability of purified MAggF to effect changes in macrophage phagocytosis and production of arachidonic acid metabolites. The effects of eicosanoids and other adherence factors in modifying response to MAggF will also be investigated. Subproject 4 will study regulation of MAggF production by thymic hormones, macrophages, and macrophage products such as alpha2 macroglobulin and eicosanoids. In this and other subprojects, MAggF will be quantitated by bioassay and by immunoassay based on anti-FN and anti-MAggF antibodies. In subproject 4 in particular, these antibodies will be used to isolate metabolically labeled MAggF to provide direct evidence for mechanism(s) regulating MAggF production by T cells.
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