The overall goal of the project is to identify and characterize macrophage products of potential importance in immune and inflammatory responses in order to manipulate these responses for clinical benefit. The project is focused on in vitro functional studies of two macrophage-derived chemokines on human bone marrow colony forming cells, and on functional studies of these and other chemokines on human lymphocytes. This laboratory identified Mig and Crg-2, two previously undescribed mouse members of a newly-defined family of small secreted proteins, termed chemokines. Crg-2 is the murine homologue of the human chemokine IP-10. Using the mouse MuMig cDNA probe, HuMig, a new human member of the family was discovered. Our mapping studies have placed the human mig and IP-10 genes to within 14 kilobases of each other on chromosome 4q 21.21 at a site distant from the cluster of other chemokine genes. Mig and IP-10 share several additional features. Both are inducible in macrophage and other cells by IFN-alpha. Both target activated T cells and share at least one receptor. Using CD34+ bone marrow cells obtained from normal donors, we have demonstrated that both recombinant HuMig and IP-10 can inhibit the stimulatory effects of the growth factor IGF-II in the production of granulocyte-macrophage colony forming units (CFU-GM), and that rHu-Mig would inhibit the IGF-II - dependent increase in the more primitive long-term culture initiating cells (LTC-IC). These results demonstrate that HuMig has myelosuppressive activity and suggest that like other chemokines HuMig might function physiologically or pharmacologically as a growth factor inhibitor. Studies of the effects of rHuMig an T-cells led to broader studies of chemokine targeting of lymphocyte subsets using a refined flow cytometric assay for calcium fluxes that allowed for simultaneous phenotypic analysis of responding cells. We demonstrated responses to eight chemokines in activated T-cells. In general, the CXC chemokines SDF-1, HuMig and IP-10 were more potent than the CC chemokines MIP-1alpha, MIP-1beta, RANTES, MCP-1, and MCP-3. Moreover, we demonstrated that the CC chemokines stimulated memory cells with little activity on naive cells, while the CXC chemokines targeted naive as well as memory cells. From these data we conclude that the CXC and CC subfamiliies differ in both potency and selectivity in their activity on T-cell subsets, presumably reflecting specific roles among the chemokines in recruitment of subsets to sites of inflammation and immune response.
Showing the most recent 10 out of 11 publications
