title: Tear IgA and serum IgG antibodies against Acanthamoeba in patients with Acanthamoeba keratitis.
abstract: OBJECTIVE
  Exposure to Acanthamoebaspecies appears to be ubiquitous, as 50% to 100% of healthy human subjects display anti-Acanthamoebaantibodies. However, the presence of specific anti-Acanthamoebaantibodies in the serum and tears of patients has not been investigated. The prevalence of serum immunoglobulin G (IgG) and tear IgA against three species of Acanthamoebawas assessed in healthy subjects and patients with Acanthamoebakeratitis.
  
  
  METHODS
  The level of specific serum IgG and tear IgA against A. castellanii, A. astronyxis, and A. culbertsoniin the sera of 23 patients and 25 healthy subjects was tested by enzyme-linked immunosorbent assays. Total serum IgM, IgG, and IgA concentrations were measured by nephelometry. Acanthamoebakeratitis was diagnosed clinically and confirmed by in vivo confocal microscopy. In some patients, corneal biopsies were also performed and trophozoites were cultured on lawns of Escherichia colion non-nutrient agar.
  
  
  RESULTS
  All healthy subjects and patients with Acanthamoebakeratitis had detectable serum IgG antibodies against all Acanthamoebaantigens. However, patients with Acanthamoebakeratitis had significantly higher anti-AcanthamoebaIgG antibody titers than healthy subjects. In contrast, Acanthamoeba-specific tear IgA was significantly lower in patients with Acanthamoebakeratitis in comparison with healthy subjects. Total serum immunoglobulins did not differ significantly between healthy subjects and patients with Acanthamoebakeratitis.
  
  
  CONCLUSIONS
  The results suggest that a low level of anti-AcanthamoebaIgA antibody in the tears appears to be associated with Acanthamoebakeratitis.
authors.affiliation: Department of Ophthalmology, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, USA. hassan.alizadeh@UTSouthwestern.edu
authors.forename: H
authors.initials: H
authors.lastname: Alizadeh
authors.forename: S
authors.initials: S
authors.lastname: Apte
authors.forename: M S
authors.initials: MS
authors.lastname: El-Agha
authors.forename: L
authors.initials: L
authors.lastname: Li
authors.forename: M
authors.initials: M
authors.lastname: Hurt
authors.forename: K
authors.initials: K
authors.lastname: Howard
authors.forename: H D
authors.initials: HD
authors.lastname: Cavanagh
authors.forename: J P
authors.initials: JP
authors.lastname: McCulley
authors.forename: J Y
authors.initials: JY
authors.lastname: Niederkorn
mesh_terms: D000048:Acanthamoeba / Q000276:immunology*; D015823:Acanthamoeba Keratitis / Q000175:diagnosis / Q000276:immunology*; D000818:Animals; D000913:Antibodies, Protozoan / Q000032:analysis*; D000953:Antigens, Protozoan / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000032:analysis*; D007074:Immunoglobulin G / Q000097:blood*; D007075:Immunoglobulin M / Q000097:blood; D008297:Male; D018613:Microscopy, Confocal; D013666:Tears / Q000276:immunology*
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007071:Immunoglobulin A, Secretory; D007074:Immunoglobulin G; D007075:Immunoglobulin M