Human T lymphocytes were deposited on glass surfaces coated with non-activating anti-HLA antibodies (A, C, E) or activating anti-CD3 antibodies (B, D, F). Cell morphology was monitored with standard microscopical observation (A, B) and interference reflection 15 minutes (C, D) or 30 minutes (E, F) after deposition. Clearly, contact extension was mediated by lamellipodia or filopodia depending of substratum structure. Bar length is 2 μm.