Peculiarities of Phagocytosis of Opsonized and Nonopsonized Bacteria S. Aureus and E. Coli by Human Neutrophil Granulocytes Studied by Atomic Force Microscopy

Abstract

Differences in the phagocytosis process of opsonized and nonopsonized strains of Staphylococcus aureus 2879 M and Escherichia coli 321 were studied. Differences in the character of pseudopodia during phagocytosis by neutrophil granulocytes (NGs) of opsonized and nonopsonized bacteria were detected, and differences in the nature of pseudopodia in reactions to gram-positive and gram-negative microorganisms were not detected. For the first time in dynamic observations at the late stages of phagocytosis, changes in the volume of nuclei and their movement, variations in the intersegment distance of the nuclei, and a slight increase in the volume of NGs were shown. A decrease in the rigidity of the membrane–cytoskeleton NG complex correlating with the intensity of phagocytosis and opsonization of bacteria was shown for the first time. It was established that opsonization does not affect the oxygen-dependent metabolism of NGs and, at the same time, introduces significant adjustments in the implementation of oxygen-independent bactericidal mechanisms of cells.