Hormonal regulation of cell surface expression of the major histocompatibility antigen H‐2Ld in transfected cells.

The murine major histocompatibility antigens are cell surface glycoproteins which play an important role in the recognition of foreign antigens by cytotoxic T lymphocytes. Modulation of the level of expression of histocompatibility antigens could therefore be useful for the study of the interaction between the antigen presenting cells and T lymphocytes. The glucocorticoid hormone‐inducible promoter, located in the long terminal repeat of mouse mammary tumor virus, was used to replace the promoter region of a cloned H‐2Ld class I gene. The chimeric gene was introduced into cultured cells. Glucocorticoid induction of MMTV LTR H‐2Ld mRNA could be shown by blot analysis. An S1 nuclease protection assay indicated that the transfected cells accurately initiate the chimeric mRNA. Immunoprecipitation of H‐2Ld protein with a specific monoclonal antibody showed inducibility also at the cellular protein level. Fluorescence‐activated cell sorter analysis monitored a 3‐fold increase of H‐2Ld on the cell surface when the transfected cells were grown in the presence of dexamethasone. This increase of H‐2Ld expression was accompanied by a corresponding decrease on the cell surface of the endogenous H‐2Kk.