Immature DCs do not form wrapping sheets around T lymphocytes in the context of the infectious synapse. IA-SEM analysis of immature and mature DC-T cell infectious synapses. (A-D) 2D images of immature DC-T cell infectious synapses from the IA-SEM image stack corresponding to slices at progressively lower locations in the image stack. Red arrows point to some of the HIV-1 particles visible in the image. (E-H) Surface representations of the image stack with top surfaces corresponding to the images shown in panels A to D, respectively. (I-J) Top slice and front surface view of IA-SEM image stack showing the entire imaged area; the boxed region corresponds to the region highlighted in panels A to D. The green spheres represent the location of HIV-1. (K-L) Comparison of the infectious synapse between mature DCs (K) pulsed with HIV-1 and CD4⁺ T cells and of immature DCs (I) pulsed with HIV-1 and CD4⁺ T cells. (K) Arrows indicate the location of the sheet-like protrusions from the mature DCs that surround the T cells. Bar represents 2 μm.