Phagocytosis and hydrophobicity: a method of calculating contact angles based on the diameter of sessile drops.
The correlation between the contact angle and degree of phagocytosis of different yeast particles has been investigated. To facilitate the estimation of the contact angle, we have tested the hypothesis that the shape of a small liquid drop put on a flat surface is that of a truncated sphere. By making this approximation it is possible to calculate the contact angle, i.e. the tangent to the drop in the 3-phase liquid/solid/air meeting point, by measuring the drop diameter. Known volumes of saline were put on different surfaces and the diameters of the drops were measured from above. Calculation of the contact angle with drops of different volumes, and comparison between expected and measured height of 10 microl drops, indicated that the assumption that the shape of a drop is that of a truncated sphere is valid. Monolayers of leukocytes was shown to give rise to a contact angle of 17.9 degrees. Particles with a lower contact angle than the phagocytic cells resisted phagocytosis, but opsonization of the particles with normal human serum rendered them susceptible to phagocytosis, conferring a higher contact angle than that of the phagocytic cells.
Dahlgren
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C
Department of Medical Microbiology, The University of Linköping, S-581 85, Linköping, Sweden.
Sunqvist
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T
D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007158:Immunologic Techniques; D007962:Leukocytes / Q000502:physiology; D008962:Models, Theoretical; D010316:Particle Size; D010587:Phagocytosis; D012441:Saccharomyces cerevisiae; D012995:Solubility; D013501:Surface-Active Agents
D013501:Surface-Active Agents