Spatial distribution of T-cell molecules in the complex with a DC or a B cell. Antigen-loaded DCs or B cells were incubated with autologous CD4⁺ T cells (expanded in the presence of an influenza vaccine) for 4 hours; TCR and CD28 were stained (green and red, respectively) and the cells fixed. By confocal optical sectioning (using a C-Apochromat 63×/1.20 W Corr lens) and 3-D reconstruction with Metamorph software we show the plane of contact between 2 cells. The x-y plane is coincidental with the plane of maximum fluorescence; the z-axis is parallel with the line connecting the centers of the T and the DC or B cell. Images are reconstructed in the x-y and x-z planes to compare the size, depth, and distribution of molecules in the respective synapses. Bars represent 1 μm.