Figure 5. NK cells accumulate F-actin at the activating NKIS internal to cell-surface receptor defined NK cell periphery.

(A) F-actin at the NKIS contributed by NK cells was measured by generating a series of 1 um² subregions across the NKIS to evaluate only F-actin selected to be within the KIR2DL1-gfp defined periphery of YTS cells. The F actin content in these subregions (“F”) was measured using the same fixed intensity threshold (left) as in Figure 4. The F-actin content inside the KIR2DL1-gfp defined periphery of unconjugated YTS cells (“G”) was measured by using the same intensity threshold and same number of 1µm² subregions used to define “F” (right).

(B–D) F-actin content (B), MFI (C) and area (D), were measured inside the inhibitory (orange circles), and cytolytic (red circles) NKIS.. Each measurement displays 19 individual cells, the horizontal bar in each series represents the mean and the vertical error bars the SD. The amount (solid circles – “F”), or NK cell accumulation (open circles – “F-G”) of F-actin at the NKIS that was in YTS-KIR2DL1 cell within its KIR2DL1-GFP-defined surface was calculated for the inhibitory and cytolytic NKIS. Differences between values for F-actin of the cytolytic and inhibitory NKIS were significant,*=p<0.05.

(E) Distance from the centroid of the grouped perforin region to the IS in YTS KIR2DL1:721.221 Cw3 conjugates (open circles) and YTS KIR2DL1:721.221 Cw4 conjugates (closed circles) is shown. The mean of all individual cell measurement (n=19 cells each) is represented by a horizontal bar within each series and the vertical bar demonstrates the SD. The difference between the perforin centroid to the IS in inhibitory and cytolytic conjugates was significant, *=p<0.05.