Derivation, culture, and characterization of thymic epithelial cell lines

The major histocompatibility complex (MHC)-restricted presentation of self-peptides, generated from tissue-specific antigens, by thymic epithelial cells (TECs) is essential for development of central tolerance and for generation of the regulatory T-cell repertoire in the thymus. However, the mechanisms by which self-peptides are generated in and presented by TECs have not been well defined. To elucidate the processes involved in MHC class II-restricted presentation of self-peptides by TECs, cortical and medullary TEC lines may be established from C57BL/6 mouse thymi. Localization of a variety of molecules, including the MHC class II molecules critically involved in the presentation of antigen by TECs, may be investigated by both immunofluores-cence microscopy and Western blotting analyses. Our own studies using these approaches have demonstrated that such molecules are localized in the H2-DM+ lysosomal compartments isolated from both cortical and medullary TECs.