Merocyanine 540 and annexin V preferentially bind to membrane blebs on calcium ionophore-stimulated lymphocytes. Confocal sections of murine mesenteric lymph node cells are shown. Lymphocytes from C57BL/10 mice were stimulated with 10 μM calcimycin and stained with 1 μM MC540 (green) or annexin V AlexaFluor 568 (red). DAPI staining of nuclear DNA is in blue. Scale bars indicate 10 μm. (A) Stack of confocal sections separated by 0.3 μm increments showing membrane blebs. (B) Single confocal sections.