Anti-Acanthamoeba IgG, IgM, and IgA immunoreactivities in correlation to strain pathogenicity

Acanthamoeba are known as causative agents of Acanthamoeba keratitis and gr anulomatous amoebic encephalitis. These occur predominantly in the immunoco mpromised host, but it is still unclear what primes the amoebae for pathoge nicity. The aim of this study was to assess possible immunological differen ces between a highly pathogenic and a nonpathogenic Acanthamoeba strain. A total of 20 sera, including two sera of Acanthamoeba keratitis patients, we re tested for anti-Acanth-amoeba IgG, IgM, and IgA immunoreactivities using immunoblotting. All sera were positive for Acanthamoeba, revealing two pre dominant bands at 29 kDa and at 47 kDa, respectively. Interestingly, IgG an d particularly IgA immunoreactivity enabled a clear discrimination between the pathogenic and nonpathogenic strains. Moreover, compared to the control sera, the two sera of Acanthamoeba keratitis patients showed rather weak i mmunoreactivities and they lacked the 29 kDa and the 47 kDa band in the IgA immunoblot against the pathogenic strain. The results of our study support the assumption that immunological predisposition might also be of importan ce in Acanthamoeba keratitis.