Atomic force microscopy of peritoneal macrophages after particle phagocytosis

The atomic force microscope was used to image peritoneal macrophages after phagocytosis of latex beads with 0.45 m in diameter and of zymosan particles. The rigidity of the phagocytosed material allowed to image the live membrane at forces below 2 nn. Repeated scanning of the membrane unavoidably caused the protrusion of the beads and increased their virtual height. The influence of fixation by glutaraldehyde on the image and the corresponding force vs. distance curves were analyzed and compared. Short treatment with Triton X-100 enabled us to identify intracellular components, such as embedded latex beads, cell nucleus and cytoskeletal strands. The data demonstrate that it is possible to image living cells if they are bolstered by stiff material.The authors wish to thank Dr. H. Oberleithner for his generous support, helpful discussions and the suggestion of Triton treatment. The authors gratefully acknowledge Dr. I. Jahns for establishing the AFM technique at the Institute of Physiology. The work was supported by the Deutsche Forschungsgemeinschaft Projekt No. La 315/4-1.