Figure 3.
Actin Flow Velocity at the IS Is Antigen Dependent
(A) Time-lapse imaging for actin bleach region and temporal projection. Top: time-lapse shows a representative cell with a stable leading edge. Bottom: time-lapse shows a representative cell in which the leading edge expands over time. Scale bar, 1 μm.
(B) Tracking of segmented bleached region in the T cell lamellipodium.
(C) Displacement of segmented bleached region with corresponding linear fit.
(D) Left: model of actin bleach region dynamics in the presence of a stable leading edge. Right: kymograph of stable leading edge, showing the bleach region edge (red dotted line) and the leading edge (blue dotted line).
(E) Left: model of actin bleach region dynamics in the presence of an expanding leading edge. Right: kymograph of the expanding leading edge (blue and green dotted lines) and the bleached region edge, showing a corresponding slowdown as the leading edge expands (red and yellow dotted lines).
(F) Antigen kinetics as shown by their solution koff for the four stimulating antigens.
(G) Distribution of actin velocity as measured by bleach region tracking for each antigen for cells exhibiting a stationary leading edge. Error bars show means and SDs; N ≥ 8 cells per condition.
(H) Distribution of actin velocity as measured by bleach region tracking for each antigen for all activating cells (expanding, stationary, and contracting leading edges). Error bars show means and SDs; N ≥ 14 cells per condition.