FIG. 1.

Downregulation of surface expression of MHC class I molecules by K3 and K5. BJAB cells were electroporated with GFP reporter, GFP-K3, GFP-K4.2, or GFP-K5 vector. The cell surface levels of MHC class I molecules were assessed 48 h posttransfection by staining the cells with a W6/32 antibody for MHC class I or TU39 antibody for MHC class II (y axis) and gating the GFP-positive cell population (x axis) by flow cytometry. Three populations of cells were distinguished by the applied gates; in the upper left quadrant are the untransfected cells, in the upper right quadrant are the GFP-positive transfected cells which have not downregulated class I or class II, and in the lower right quadrant are the GFP-positive transfected cells that have downregulated class I or class II. The data were reproduced in three independent experiments.