Interferon treatment of HEp‐2 cells alters the adhesive ability of Pseudomonas aeruginosa

Abstract

Previous studies have shown that interferons specifically interact with HEp-2 cells and reduce invasiveness by Salmonella and Shigella. In this study an effect of interferons on the adhesiveness of a strictly extracellular bacterium was demonstrated. HEp-2 cells were treated with human leukocyte interferon, recombinant interferon alpha-A or recombinant interferon gamma and the adhesiveness of Pseudomonas aeruginosa to the cells was examined using a light microscopy method. A recent isolate and a variant of the same strain subcultivated for 12 months were used. Treatment of cells with human leukocyte interferon or recombinant interferon alpha-A reduced the adhesiveness of both variants. When recombinant interferons were used a dose dependent effect was observed, whereas the effect after treatment with human leukocyte interferon was not dose dependent. Adhesiveness of the bacteria to HEp-2 cells was reduced after subcultivation of the bacteria but was reconstituted by adding an extracellular filtrate from the recent isolate. This extracellular filtrate inhibited the effect of human leukocyte interferon on the adhesiveness of bacteria in the cell cultures. The human leukocyte interferon effect on bacterial adhesiveness was neutralized by anti-interferon globulin. Treatment of HEp-2 cells with recombinant human gamma interferon caused an enhanced adhesiveness of the recent isolate, but reduced the adhesiveness of the subcultivated variant strain.