Mannose induces the release of cytopathic factors from Acanthamoeba castellanii

Henry Leher, Robert Silvany, Hassan Alizadeh, Jing Huang, Jerry Y. Niederkorn

Research output: Contribution to journalArticlepeer-review

80 Scopus citations


Acanthamoeba keratitis is a chronic inflammatory disease of the cornea which is highly resistant to many antimicrobial agents. The pathogenic mechanisms of this disease are poorly understood. However, it is believed that the initial phases in the pathogenesis of Acanthamoeba keratitis involve parasite binding and lysis of the corneal epithelium. These processes were examined in vitro, using Acanthamoeba castellanii trophozoites. Parasites readily adhered to Chinese hamster corneal epithelial cells in vitro; however, parasite binding was strongly inhibited by mannose but not by lactose. Although mannose prevented trophozoite binding, it did not affect cytolysis of corneal epithelial cells. Moreover, mannose treatment induced trophozoites to release cytolytic factors that lysed corneal epithelial cells in vitro. These factors were uniquely induced by mannose because supernatants collected from either untreated trophozoites or trophozoites treated with other sugars failed to lyse corneal cells. The soluble factors were size fractionated in centrifugal concentrators and found to be ≤100 kDa. Treatment of the supernatants with the serine protease inhibitor phenylmethylsulfonyl fluoride inhibited most, but not all, of the cytopathic activity. These data suggest that the binding of Acanthamoeba to mannosylated proteins on the corneal epithelium may exacerbate the pathogenic cascade by initiating the release of cytolytic factors.

Original languageEnglish (US)
Pages (from-to)5-10
Number of pages6
JournalInfection and immunity
Issue number1
StatePublished - 1998

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases


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