Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 5 1 2010 03 15 35 40 EN M Eftekhar Dept. of Parasitology, School of Medicine, Shahid Beheshti University, M. C., Tehran, Iran A Athari Dept. of Parasitology, School of Medicine, Shahid Beheshti University, M. C., Tehran, Iran A Haghighi Dept. of Parasitology, School of Medicine, Shahid Beheshti University, M. C., Tehran, Iran N Mosaffa Dept. of Immunology, Shahid Beheshti University, M. C., Tehran, Iran F Shahram Rheumatology Research Center, Tehran University for Medical Sciences, Iran A Abadi Dept. of Community & Health, Shahid Beheshti University, M. C., Tehran, Iran 2015 10 03 Background: This preliminary study was conducted to discriminate the prevalence of Acanthamoeba an­tibodies in rheumatoid arthritis (RA) patients and healthy controls to analyze the correlation between these two groups. Methods: From October 2006 to August 2007 a total of 121 serum samples from RA patients attending the Rheumatolgy Department at Shariati Hospital in Tehran were obtained and stored at -20°C until using by indirect fluorescent-antibody test (IFAT). RA was diagnosed according to the American Collage of Rheumatology classification criteria.  The organism used in this study was isolated from various water resources in Tehran, Iran cultured axenically and then went on a PCR assay based on 18S rRNA to iden­tify the genus Acanthomoeba. Indirect immunofluorescence antibody (IFA) staining of serum samples was carried out to detect anti Acanthomoeba antibodies. Results: In culture, out of 22 samples, 13(59%) were grown in xenic but only two in axenic medium. PCR amplified a 904bp fragment, specific for Acanthamoeba. Of examined serum samples, Acanthamoeba an­tibodies were present in 70 (57.8%) and 52 (41.2%), respectively. The highest titer of antibodies (1:320) was detected in one patient with RA. Conclusion: Our study supports the hypothesis that some parasitic microorganisms can involve and con­tribute toward the development of rheumatoid syndromes. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/124 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/124/123