Interaction between Salmonella bacteria and mammalian nonprofessional phagocytes.

A series of lipopolysaccharide mutants of Salmonella typhimurium and Salmonella minnesota were studied regarding their interaction with HeLa cells. The bacteria differed in physicochemical surface properties, with respect to charge and propensity to hydrophobic interaction. Mutants with propensity to hydrophobic interaction and/or negative charge attached to and were internalized into HeLa cells to a greater extent than bacteria lacking such surface properties. Heat-killed and ultraviolet-killed bacteria did not attach to HeLa cells. Metabolic and ultrastructural studies showed that Salmonella bacteria were internalized into HeLa cells by an endocytic process. Hyperimmune IgG and other proteins may inhibit this ingestion.