(A) Schematic experimental flow of the analysis of IS formation and function between NEF-expressing CD4OT-II cells and antigen-specific BHEL cells. BHEL cells were stimulated with LPS in the presence (+Ag) or absence (-Ag) of HEL-OVA antigen. B cells and T cells were labelled with different CellTrackerTM dyes before seeding on PLL-coated cover glasses and analyzed by microscopy. 