Figure 1.

The FLAG foreign epitope did not alter CIITA activity. (A) FLAG.CIITA8 activated the DRA promoter in G3A cells. G3A cells were cotransfected with the pDRA300CAT construct and an empty vector (lane 1), CIITA expression vector (lane 2), or FLAG.CIITA8 (lanes 3 and 4). The cells were harvested and analyzed for CAT activity 48 h after transfection. (B) FLAG.CIITA8 induces HLA-DRA expression on the MHC class II-negative G3A mutant cells. 2fTGH cells (Ba and Bb), G3A (Bc and Bd), and G3A (Be and Bf) stably integrated with FLAG.CIITA8 were not treated (Left) or treated (Right) with 500 units/ml of IFN-γ for 72 h. The cells were harvested and analyzed for surface HLA-DR antigen expression by a FACScan (Becton Dickinson).