The Influence of the Shape of Phagocytes on their Adhesiveness

Abstract

Glucose is known to depress the adhesiveness to glass as well as the phagocytic activity of neutrophils and macrophages. Contact angle measurements indicate that this is not due to any decrease in cell surface free energy. The decreased adhesiveness to glass and depressed phagocytic activity under the influence of glucose are instead found to be due to the fact that glucose causes the phagocytes to retract their pseudopods and to become spherical in shape. It can be shown that a spherical shape tends to enhance the electrostatic repulsion between cells and between cells and other surfaces, while pseudopods help to overcome that electrostatic repulsion. It is also shown that heparin does not interfere with the normal bizarre shape of neutrophils, while other anticoagulants such as ADP, CPD, and EDTA(for explanation of the symbols, see below) cause the neutrophils to become spherical. This explains why only when heparin is used as an anticoagulant, neutrophils will adhere to glass or nylon surfaces, and thus can be removed from whole blood by filtration through these media. Finally, it could be demonstrated that platelet adhesiveness is also caused by the induction of a spiculated cell shape, rather than by a change in cell surface free energy. It was previously noted by one of us (1) that human neutrophils, under in vitro conditions of high (4 and 8mg/ml) glucose levels, manifested a significant depression of their phagocytic activity as well as a decreased adhesiveness to glass surfaces. A similar effect of glucose on guinea pig macrophages has also been observed (2). We have since established that the depressed phagocytic activity and the decreased adhesiveness to glass at high glucose levels are not due to changes in the surface free energy of the phagocytes (see belaw). In view of the important role played by pseudopodic protrusions of the electro-negatively charged cells in their adhesion to other negatively charged surfaces (3), we proceeded to investigate the influence of glucose and a number of other additives on the shape of phagocytic cells.