Fig. 2

Morphological changes correlated with sustained Ca²⁺ signals in CD4⁺ T cells. a Shape index changes and Ca²⁺ signals in a CD4⁺ T cell whose morphology changed to elongated-flattened (top panel). Phases I, II, and III refer to contact, recognition, and interaction, respectively. Images of the morphology and Ca²⁺ signals of the elongated-flattened T cell in the three phases are shown in the left panel at the bottom. The contrast between the edges and the middle of the cell changed at 200 s and 1040 s (right column of the left-hand bottom panel). b Shape index changes and Ca²⁺ signals in a CD4⁺ T cell whose morphology changed to flattened (top panel) during the three phases. Images of the morphology and Ca²⁺ signals of the round-flattened T cell in the three phases are shown in the left panel at the bottom. The contrast between the edges and the middle part of the cell changed at 240 s and 300 s (right column of the left-hand bottom panel). The dotted white line depicts the contact boundary between the OT-II CD4⁺ T cells and the DCs. c Shape index changes and Ca²⁺ signals in a single resting CD4⁺ T cell. The contrast between the edges and the middle of the cell changed at 600 s (right column of the left-hand bottom panel). (A-C) Ca²⁺ signalling was observed every 10 s or 40 s. The calcium signal intensity was pseudo-colored with hues ranging from blue (low) to red (high). ICAM-1 was labelled to be green, TCR was labelled be red. Before IS formation, TCR was uniformed on the surface of T cell. After IS formation, TCR and ICAM-1 were accumulated into the IS of DC-T. d Average Ca²⁺ responses in CD4⁺ T cells whose morphology changed to round-flattened (625±74 nM, n=50) or elongated-flattened (294±46 nM, n=50). The average Ca²⁺ response in the resting CD4⁺ T cells was 57±23 nM (n=50; the data are shown as the mean ± s.e.m., two-tailed Student’s t-test, ***P<0.001). Scale bar = 2 μm