Image from the NFDI4BIOIMAGE Calendar September 2025. The scanning electron micrograph shows the approach of T-lymphocytes (Jurkat cells; cyan) to an antigen-presenting B cell (Raji cell; yellow) in the center. The image was taken as part of the research work of the CRC 854, which focused on molecular processes that regulate inter- and intracellular communication within the immune system. Image Metadata (using REMBI template): Study Study description Ultrastructure of the immune synapse Study type Research project within DFG CRC 854 (Molecular organisation of cellular communication within the immune system) Study Component Imaging method Scanning Electron Microscopy Biosample Biological entity Jurkat cell line E6.1 and Raji B cell lymphoma cell line Organism Homo sapiens Identity Z21_A1 Specimen Preparation method Cell lines were maintained in RPMI 1640 medium supplemented with 10% fetal calf serum (FCS; PAN Biotech), stable L-glutamine, penicillin (50 U/ml), and streptomycin (50 mg/ml) (Biochrom) in humidified 5% CO2 at 37°C. E6.1 cells were mixed at a 1:1 ratio with Raji B cells that had been pulsed with SEE (bacterial SAG staphylococcal enterotoxin E). After 10 min cells were plated on poly-L-lysine–covered slides at room temperature for 5 min and fixed for 10 min in PBS (pH 7.4) containing 1.5% PFA and 0.025% glutaraldehyde. Cryo-drying by critical point dryer (Leica EM CPD300) followed by sputtering with gold. Signal/contrast mechanism Detected secondary electrons Channel 1 - content Jurkat cell line E6.1 (artificial color table, cyan) Channel 1 - biological entity Surface of Jurkat cells Channel 2 - content Raji B cell lymphoma cell line (artificial color table, yellow) Channel 2 - biological entity Surface of a Raji B cell Image acquisition Instrument attributes FEI XL30 FEG ESEM Image acquisition parameters 10 keV, Magnification 6500 x, Scale bar: 2 µm Submitted via NFDI4BIOIMAGE