Efficient cDNA expression vectors for stable and transient expression of HLA-DR in transfected fibroblast and lymphoid cells

cDNA expression vectors with several useful features were constructed. First, the long terminal repeat of Rous sarcoma virus was used as a promoter to obtain high levels of expression in various cells of human and mouse origin. Second, cis-linked expression units that confer resistance either to mycophenolic acid or the neomycin analog G418 were inserted to facilitate the isolation of transfected cells expressing the cDNA of interest. Third, by replicating in simian COS cells, these vectors can be used for efficient transient expression. cDNA fragments encoding the DRα or DRβ chains of human class II major histocompatibility complex antigens were inserted into these vectors and high levels of cell surface HLA-DR antigen were obtained after contransfection into mouse and human fibroblasts. These vectors were also successfully used to correct the inability of a class II-negative B cell line, derived from a patient with a congenital immunodeficiency, to present peptide antigen to DR-restricted T cells.