Figure 5

Cell clones developed from total populations of stably transfected TF-1 and U-937 cell lines reflect the green fluorescent protein (GFP) expression profile of the parental populations. The TF-1 and U-937 cells that were stably transfected with the LAI long terminal repeats (LTR) (wild-type [WT], 3 T, 5 T, and 3T5T) were serially diluted in order to obtain 1 cell in 1 mL of media (approximately 1 cell in 10 wells of a 96-well plate). Cell clone populations were propagated from a single cell and then were analyzed using flow cytometry for their basal GFP expression. The clonal populations were then designated in one of three categories (nonexpresser, intermediate expresser, and high expresser) based on their geometric mean fluorescence intensity (MFI) and their percent cell positive values (A). Representative histograms showing levels of GFP expression by the stably transfected cell clone (black line) compared with the untransfected control cell line (gray line) for TF-1 (B), U-937 (C), cell clones expressing the LAI WT, 3 T, 5 T, or 3T5T LTRs. The histograms show that the TF-1 and U-937 cell clones mimic their parental population counterparts in terms of basal GFP expression profiles. Tables below each set of histograms show the total number of clonal cell populations for each LTR genotype that falls within one of the three expression phenotypes.