Mahmoudi, Mahmoud, Immunology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran; Department of Immunology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. Tel: +98 9151156304, Fax: +98 5138022229, E-mail: MahmoudiM@mums.ac.ir, Iran, Islamic Republic of