The goal of these studies is an in-depth investigation of the thymus derived lymphocyte and its products. Lymphotoxin (LT), a product of antigen or mitogen activated T cells, is being studied as a model lymphokine. The long term goals are to study LT's cell of origin, biochemical nature, mechanism of action, relationship to other lymphokines, regulation and role in vivo. Murine lymphotoxin cDNA has been cloned with mRNA from an interleukin-2 maintained T cell clone. Its gene has been isolated and mapped to chromosome 17.
The specific aims of the next 5 years are to analyze the structure of the LT gene, to precisely localize it on chromosome 17, to determine the linkage relationship of the genes for LT and tumor necrosis factor (TNF), to obtain maximal expression of LT cDNA, to analyze regulation of LT and TNF, to study expression of the transfected LT gene and to analyze the 5' regulatory sequence of the LT gene. Goals will be accomplished by sequencing the gene, by identifying LT promoter activity, and by expressing LT DNA in prokaryotic and eurkaryotic cells. Interleukin-2 maintained T cell clones will be exposed to several inducing agents and their LT and TNF mRNA analyzed by Northern blots. The murine LT gene will be ligated to strong promoters and its expression studied in human T cell tumors. Similar vectors will be used to study the effect of LT gene overproduction in transgenic mice. Such mice will be analyzed for autoimmune pathology. If the LT gene is overexpressed in the T cells of these mice, and those cells killed, a murine model for AIDS will be available. LT 5' regulatory sequences will be ligated to a neutral gene, chloramphenical acetyle transferase, in order to study regulation of the LT gene in the absence of effects attributable to the product itself. Studies with transfected T cells, B cells, macrophages and transgenic mice will provide insigt into the nature of T cell specificity of LT expression and eventually lead to an understanding of the molecular basis of LT gene activation by antigen.
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