Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 11 4 2019 09 17 337 344 Mahsa Banaei Applied Microbiology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran AND Department of Biology, Central Tehran Branch, Islamic Azad University, Tehran, Iran Gholam Hosein Alishiri Department of Rheumatology, School of Medicine, Baqiyatallah University of Medical Sciences, Tehran, Iran AND Chemical Injuries Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran Ramezan Ali Ataee Applied Microbiology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran AND Department of Medical Microbiology, School of Medicine, Baqiyatallah University of Medical Sciences, Tehran, Iran Ardeshir Hesampoor Mahalati Department of Biology, Central Tehran Branch, Islamic Azad University, Tehran, Iran 2018 10 16 2019 06 23 Background and Objectives: Microbial superantigens have been reported in the blood and synovial fluid of rheumatoid arthritis patients, raising the question of whether the presence of these superantigens could provoke the induction of inflammatory biomarkers expression or not. The purpose of this study was to examine the Staphylococcus aureus superantigen C on CD18 expression. Materials and Methods: The superantigen C was purified by ultrafiltration. Immunoblotting was performed using a specific antibody. Also, 50 micrograms of superantigens (toxin) were injected intraperitoneally and intra-articularly into separate rat groups. Blood was collected and RNA extracted. Then, the cDNA was synthesized. The expression of CD18 marker was evaluated using RT-real-time PCR, and the results were descriptively analyzed. Results: The results of this study revealed that 50 μg of toxin, injected intra-articularly and intraperitoneally, showed the surplus expression of the marker CD18 in the blood of rats after 20 days. By this method, the expression of the marker CD18 was significantly different between rats that received the superantigen intra-articularly and intraperitoneally (2.10; 2.3 and 3.3 folds) and the controls (P≤ 0.05). Conclusion: The results indicated that the presence of Staphylococcal of superantigen C in the body of rats has enhanced the expression of the CD18 inflammatory marker more than 3 times. This valuable finding is an introduction to further research and could provide new methods to prevent and control inflammatory diseases, including rheumatoid arthritis. https://ijm.tums.ac.ir/index.php/ijm/article/view/1924 https://ijm.tums.ac.ir/index.php/ijm/article/download/1924/1186