Phagocytosis as a surface phenomenon. V. Contact angles and phagocytosis of rough and smooth strains of Salmonella typhimurium, and the influence of specific antiserum.

The angle made by a drop of saline in contact with a monolayer of Salmonella typhimurium or phagocytic cells, the contact angle, is a measure of their relative interfacial tension, and is predictive of a successful phagocytosis. Smooth strains of S. typhimurium possess a contact angle lower than the phagocytic cells and resist phagocytosis. Rough strains have an angle higher than the phagocytes and are readily engulfed. The lower contact angle of smooth strains can be increased by treatment with specific antibody resulting in more efficient phagocytosis.