T cells localize preferentially in follicular structures found in the spleen. Spleen tissue with follicular structures stained with anti-CD20 (green) and anti-CD3 (red) mAbs. Images were taken with an Olympus IX70 confocal microscope, at 25°C, with the use of UPlanAPO 10×/0.40 objective. Antibodies were labeled with DyLight 488 and 649 (Jackson ImmunoResearch Laboratories Inc) excited with one 30-mW argon laser at 488 nm and one 5-mW helium-neon laser exciting at 633 nm. Samples were mounted in SlowFade Gold antifade reagent and data acquired with proprietary image acquisition software (Olympus).