Analysis of the β-gal-positive cells after transfection of HMØs with β-gal and nef cDNA conjugated with transferrin-poly (L-lysine). A replication-deficient AD, dl312 was added to mediate HIV-1 nef and β-gal transfection. The transfected MØs were washed and resuspended in PBS; the resuspended cells were then placed in a poly(L-lysine)-coated 96-well plate, fixed, and stained for β-gal. The experiment was repeated four times and a representative field is shown. (a) shows the nontransfected HMØs that are negative in β-gal staining. (b) shows HMØs transfected with AD, dl312 and the β-gal plasmid. Fields were chosen to show distinct β-gal staining. Positive cells are blue and are shown with white arrows. A dividing MØ with positive β-gal staining is indicated with a red arrow. Microscopic examination of apoptotic cells identified by condensation of cytoplasm and chromatin in HMØs transfected with HIV-1 nef (c and d). MØs were cultured on slide chambers after transfection; cells were fixed in 10% neutral-buffered formalin and stained with the ApopTag peroxidase kit. A red arrow shows unstained apoptotic cells with blebbing (c). A single stained apoptotic cell (red arrow) and many unstained nonapoptotic cells (white arrows) are shown in (d).