SEE-induced polarization of MVB and MTOC to the immune synapse and calculation of their polarization indexes.
Panel A), In the left panels, synaptic cell conjugates made by Jurkat cells with CMAC-labeled, SEE-pulsed Raji cells (blue) were fixed, permeabilized and stained with anti-CD63 (red) and anti-pericentrin (magenta) antibodies to label MVB and the MTOC, respectively. The white arrow indicates the IS area. In the right-side scheme, the distances in color (“A”, blue; “B”, cyan and “C”, black) used for the calculation of both MVB and MTOC PI (A/C and B/C, respectively) are indicated. The dark-red dot represents the cell geometric center (Cellc), whereas the yellow and green dots indicates the MTOC and MVB center of mass (MTOCc and MVBc), respectively. The line “C” represents the distance between the Cellc and the synapse, and the projections of both MTOCc and MVBc on the “C” line are labelled with red crosses (MTOC/MVBproj). Since the CellC position was taken as the origin to measure distances, those “A” or “B” values in the opposite direction to the synapse were taken as negative. Thus, PI ranged from +1 to -1. The Raji cells and the Jurkat clones are labelled with discontinuous and continuous white lines, respectively. Panel B), C3 control and PKCδ-interfered P5 clone were untransfected (Control YFP–) or transfected with FMNL1-interfering (shFMNL1-HA-YFP). Subsequently, cells were challenged with CMAC-labelled, unpulsed (SEE-) or SEE-pulsed (SEE+) Raji cells for 1 h, fixed, stained with anti-pericentrin (magenta) to label the MTOC and imaged by epifluorescence microscopy to measure MTOC PI as indicated in panel A. The dot plot shows the MTOC PI of each indicated cell group are shown. NS, not significant; ***, p ≤0.05. Results and ANOVA analyses are representative of the data from several independent experiments (n=3) with similar results.