This is a revised proposal for the continuation of studies on the role of TSP and its receptors in the inflammatory response. The hypothesis to be tested is that the heterogeneous responses of PMNs and monocytes to TSP result from differences in the TSP receptors (TSP-R) that occur during development. Specific Aim 1 addresses the role of TSP in phagocyte functional responses. Functional studies on human peripheral blood monocytes will be conducted while continuing the characterization of PMN- and differentiated HL-60 cell-TSP interactions. It will also be determined if PMN and monocyte adherence to TSP induces inflammatory cytokine gene expression. Specific Aim 2 uses the HL-60 cell model to test the hypothesis that TSP differentially affects monocyte and PMN behavior through differences in TSP-R expression during differentiation. The ability of TSP to induce or alter the differentiation of HL-60 cells will be evaluated. Similar studies will be undertaken on monocytes. Recombinant cDNA technology will be utilized to reduce the expression of TSP in undifferentiated HL-60 cells to evaluate HL-60 differentiation and TSP-R expression in the absence of the ligand. Specific Aim 3 continues and extends the TSP binding studies to further characterize the receptor. This receptor will be identified and isolated from both PMNs and monocytes by standard biochemical techniques and expression cloning. Using differentiated HL-60 cells, it will be determined if phagocytes express proteoglycan receptors that can interact with the heparin binding domain (HBD) of TSP. Specific Aim 4 will examine the interaction of the TSP-R with the cytoskeleton, and determine if these receptors are associated with G-proteins.