Increased surface expression of dileucine-mutated chimeric receptor. (A) Overlay histogram plots showing fluorescence intensity of transduced TG-B T cells that are unstained or stained with PE-labeled H-2K^b-specific antibody. Viable cells were gated based on forward and side scatter. Control basal fluorescence was identical for cells transduced with either the mutated or unmutated receptor (data not shown). Control MSCV vector-transduced cells also did not detectably stain with H-2K^b-specific antibody (data not shown). (B) Staining results from 3 independent transduction experiments, each denoted by a unique symbol (♦, ▴, ▪), are compared. In each experiment an increase in the mean fluorescence intensity (MFI) of the dileucine-mutated receptor versus unmutated receptor is apparent. (C) Chimeric receptor (anti-K^b) expression is plotted as a function of cotranscribed GFP level. Transduced cell populations were analyzed for GFP (FL1) expression level and gated into regions comprising approximately 0.2 to 0.3 log fluorescence using Cellquest software (BD Biosciences, San Jose, CA). For cells within each of these gated regions, FL1 MFI (GFP) and FL2 MFI (anti-K^b staining or control unstained) was calculated and plotted.