The level of expression of the class-I major histocompatibil-19 and 54kDa. The El region encompasses those viral genes ity (MHC) antigen was determined in a series of human em-expressed first following lytic infection and is also that area bryo cell lines transformed with either adenovirus I2 (Ad 12) responsible for the acquisition and maintenance of the transearly region ' (El) Or adenovirus formed phenotype (for reviews see Bernards and van der Eb, 1987). activated N-ras DNA. MHC class-I antigen expression was greatly reduced in all Ad I 2 transformants, compared to primary cells. Expression was also reduced in the Ad 5 cell lines In view of the interesting data obtained with adenovirustransformed with E I A and EIB DNA, but levels were near transformed rodent cell systems, we have undertaken an extennormal in those lines with only E I A D N A present. Amounts sive investigation of the level of expression of MHC c1ass-I of MHC class-I antigen on the cell surface. as determined by antigen in a series of human cell lines produced after transfor-RIA and FACS analysis, generally reflected total cellular levels mation with either Ad 12 or Ad 5 EI DNA. I,, addition, the as determined by Western blotting. Expression of p2 microwas also much reduced in those cell lines with low effect on MHC of substituting the activated N-ras gene for the levels of M H C class-I antigen. The treatment of primary cells and all the transformants with human y-interferon resulted in increased expression of HLA on the cell surface. Infection of primary human cells with Ad I 2 or with a series of Ad I2 mutants did not have any effect on the MHC class-I antigens Virus infections present.
Primary human embryo kidney cells (HEKs) were grown on 9 cm plastic Petri dishes in Dulbecco's modified Eagle's me-Class-I major histocompatibility complex (MHC) antigens dium (DME) supplemented with 10% FCS. Cells were inare glycoproteins present on the surface of almost all mam-fected with Ad 12 wild-type or mutant viruses at 50 and 200