Local and systemic humoral immune response during acute and chronic Acanthamoeba keratitis in rabbits.
OBJECTIVE
To study local and systemic antibody responses during the course of acute and chronic Acanthamoeba keratitis in a rabbit model. The role of secretory IgA (sIgA) in innate and adaptive immunity is investigated.


METHODS
Acanthamoeba keratitis was induced by intrastromal injection of live trophozoites in rabbits with and without prior oral immunization with aqueous Acanthamoeba antigen. The severity score of the ensuing keratitis was followed. Anti-Acanthamoeba antibodies in tears and sera were determined before infection and on a weekly basis postinfection for 6 weeks. The role of mucosal IgA as a link between the innate and adaptive immunity to Acanthamoeba was evaluated.


RESULTS
Acanthamoeba keratitis was significantly milder in animals infected after oral immunization than in naïve animals. Mucosal sIgA bound Acanthamoeba in a concentration-dependent, mannose-mediated manner. It significantly inhibited Acanthamoeba binding to rabbit corneal epithelium in vitro and in vivo. Anti-Acanthamoeba IgA significantly influenced amoebic lysis by neutrophils.


CONCLUSIONS
Mucosal IgA protects the external ocular surface by virtue of anti-adhesin properties displayed by the mannosylated residues on the heavy chains of IgA molecule (innate immunity) as well as specific antigen-binding sites (adaptive immunity). Immune IgA also augmented neutrophil-mediated amoebic lysis (adaptive immunity).
Said
Neveen A
NA
Parasitology Department, Research Institute of Ophthalmology, Giza, Egypt. nsaid@mail.mcg.edu
Shoeir
Ahmed T
AT
Panjwani
Noorjahan
N
Garate
Marco
M
Cao
Zhiyi
Z
D000048:Acanthamoeba / Q000276:immunology*; D015823:Acanthamoeba Keratitis / Q000276:immunology*; D000208:Acute Disease; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D000917:Antibody Formation; D000953:Antigens, Protozoan / Q000276:immunology; D015153:Blotting, Western; D002908:Chronic Disease; D003319:Corneal Stroma / Q000469:parasitology; D004195:Disease Models, Animal; D019084:Fluorescent Antibody Technique, Indirect; D007113:Immunity, Innate; D018928:Immunity, Mucosal; D007071:Immunoglobulin A, Secretory / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology; D011817:Rabbits; D013666:Tears / Q000276:immunology*
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007071:Immunoglobulin A, Secretory; D007074:Immunoglobulin G