9218859 Guyden Thymic nurse cells (TNCs) are specialized epithelial components that contain T cells completely enclosed in intra-cytoplasmic vacuoles. Very little information about their function has been reported because of the lack of pure TNC populations in quantities necessary for their thorough analyses. Recently, this laboratory has been able to immortalize TNCs with SV40 virus. Cells from these TNC lines have been shown to maintain the ability to internalize thymocytes in vitro. Further, it has been shown that the only cells bound by an internalized into TNCs are CD4- positive, CD8-positive thymocytes. These cell lines will be used to study TNC function. The goals of this research are to determine the molecular components involved in TNC binding and internalization of thymocytes, and to determine the specific function of TNC internalization of double positive thymocytes in T cell development. Two strategies will be employed: (1) TNC- specific monoclonal antibodies (mAb) will be generated in an attempt to identify the receptor/ligand involved in binding and internalization. (2) Antibody preparations shown to block binding of thymocytes to TNCs will be used to clone the gene(s) expressing the protein(s) involved. These studies are designed to determine the function of thymocyte binding and internalization by TNCs. %%% Thymic nurse cells are specialized epithelial cells of the thymus in which T-lymphocytes are regularly found completely enclosed in intra-cytoplasmic vacuoles. This is a very unusual phenomenon in physiology. Very little information about the function of thymic nurse cells is known because of the lack of pure TNC populations in quantities necessary for their thorough analyses. However, they are believed to play an important role in the development of T- lymphocytes of the immune system. With prior NSF support, this laboratory has been able to grow pure populations of thymic nurse cells in culture. The goals of this project a re to study the interaction of thymic nurse cells with T-lymphocytes at the molecular level. The results of this research should provide unique new information on how thymic nurse cells function. ***
