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Figure 5 | BMC Immunology

Figure 5

From: Nitric oxide/cGMP pathway signaling actively down-regulates α4β1-integrin affinity: an unexpected mechanism for inducing cell de-adhesion

Figure 5

Changes in cell adhesion between U937 FPR (ΔST) and VCAM-1-transfected B78H1 cells in the resting state and in response to receptor stimulation. Real-time aggregation experiments were conducted as described under "Methods". U937/ΔST FPR stably transfected cells, which constitutively express VLA-4, were labeled with red fluorescent dye, and B78H1/VCAM-1 transfectants were stained with green fluorescent dye. Labeled cells were preincubated for 10 min at 37°C with fMLFF only (100 nM, activated control), DMSO (vehicle, resting cells control), or with fMLFF and DEA-NONOate (250 μM, nitric oxide donor) in a manner analogous to the experiment showed in Figure 2A. Next, cells were mixed and real-time cell aggregation (red and green double positive events) was followed. To determine the level of VLA-4 dependent cell aggregation, 6 min after cell mixing, excess unlabelled VLA-4 specific ligand was added (arrow, LDV block, 2 μM). This induced rapid cellular disaggregation to the level of non-specific binding. A representative experiment out of three experiments is shown.

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