title: Effect of human tears on acanthamoeba-induced cytopathic effect.
abstract: OBJECTIVE
  To determine whether tears of healthy individuals provide protection against Acanthamoeba-induced cytopathic effect (CPE) in vitro.
  
  
  METHODS
  Acanthamoebae were added to confluent cultures of corneal epithelium in 24-well plates, and co-cultures were incubated overnight in a serum-free medium containing varying amounts of tears or immunoglobulin A (IgA)-depleted tears. At the end of the incubation period, the cells were stained with Giemsa, and the extent of target cell damage (ie, CPE) was quantified.
  
  
  RESULTS
  Acanthamoebae produced extensive CPE. The presence of even a low concentration of tears (10 microL of undiluted tears per milliliter of media) almost completely inhibited Acanthamoeba-induced CPE. The CPE was inhibited by pretreatment of the parasites with tears. In contrast, the pretreatment of host cells with tears was not protective. This finding suggests that the target of the inhibitory factor is the parasite. IgA-depleted tears also inhibited Acanthamoeba-induced CPE, albeit with a lower potency than total tears.
  
  
  CONCLUSIONS
  In addition to known IgA-dependent protective factors, human tears contain factors that inhibit Acanthamoeba-induced CPE independently of IgA. Clinical Relevance Identification and characterization of factors that protect against Acanthamoeba-induced CPE should help in the development of novel, rationally designed strategies to manage and protect against keratitis.
authors.affiliation: Department of Ophthalmology, Tufts University School of Medicine, Boston, MA 02111, USA.
authors.forename: Zhiyi
authors.initials: Z
authors.lastname: Cao
authors.forename: Chandrassegar
authors.initials: C
authors.lastname: Saravanan
authors.forename: Michael H
authors.initials: MH
authors.lastname: Goldstein
authors.forename: Helen K
authors.initials: HK
authors.lastname: Wu
authors.forename: Gunisha
authors.initials: G
authors.lastname: Pasricha
authors.forename: Savitri
authors.initials: S
authors.lastname: Sharma
authors.forename: Noorjahan
authors.initials: N
authors.lastname: Panjwani
mesh_terms: D048248:Acanthamoeba castellanii / Q000502:physiology*; D000328:Adult; D000818:Animals; D002478:Cells, Cultured; D019573:Epithelium, Corneal / Q000469:parasitology*; D005136:Eye Proteins / Q000502:physiology; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000502:physiology; D011817:Rabbits; D013666:Tears / Q000502:physiology*
chemical_list: D005136:Eye Proteins; D007071:Immunoglobulin A, Secretory; C042434:tear proteins