Fig 2. The methodology used to study interaction forces between T-cells and dendritic cells.

The optical trap (red spots) was used to bring the cells into contact (i). As soon as contact was made (ii), the trap was blocked and the cells left to interact for a given period of time (iii—iv). Subsequently, the trap was re-instated 5 μm from the T cell (v) and the laser beam power incrementally increased until the T-cell was released from the dendritic cell and held by the optical trap, breaking cell contact (vi). The scale bar represents 4μm.