Figure 3. The C4B6⁻ cells have potent phagocytic activity.

(A) A representative histogram showing the phagocytic activity (left panel) of the C4B6⁻ cells. Increased peak fluorescence indicates an increased number of ingested beads. The colors of the markers reflect the colors in the dot plot (middle panel). The dot plot shows the distribution of cells with various number of cells; cells without beads are shown as black dots, cells with one bead are red, cells with two beads are green, cells with three beads are blue and cells with more than three beads is shown as purple. Right panel, Diff Quick stained cells with various numbers of ingested beads. (B) TEM analyses of C4B6⁻ cells with beads. Left panel, a representative cell containing several 1 µm beads (magnification = 20 000×, scale bar = 1 µm). Middle panels, cells containing beads that are 2 µm (magnification = 15 000×, scale bar = 1 µm). Right panel is an enlargement of the delimited area of the middle, right panel showing beads that are just about to be ingested (magnification = 30 000×, scale bar = 0.5 µm). (C) SEM of C4B6⁻ cells ingesting beads that are 1 µm (two left panels) and 2 µm (two right panels). Notice the cell membrane that is about to enclose around the beads. A typical thrombocyte, containing one 2 µm bead, is shown in the right panel for comparison. In panels from left to right: Magnification (scale bar); 10 000× (1 µm), 30 000× (0.3 µm), 10 000× (1 µm) and 5000× (1 µm). (D). Different stages of bead capturing. Notice the veil (arrow). In panels from left to right: Magnification (scale bar); 8000× (1 µm), 5000× (1 µm) and 6500× (1 µm).