Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 21 4 2022 08 12 458 466 EN Sara Kashef Department of Allergy and Clinical Immunology, Shiraz University of Medical Sciences, Shiraz, Iran Mozhgan Moghtaderi Allergy Research Center, Shiraz University of Medical Sciences, Shiraz, Iran Hamid Reza Hatami Department of Allergy and Clinical Immunology, Shiraz University of Medical Sciences, Shiraz, Iran Mehdi Kalani Prof. Alborzi Clinical Microbiology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran Soheila Alyasin Department of Allergy and Clinical Immunology, Shiraz University of Medical Sciences, Shiraz, Iran AND Allergy Research Center, Shiraz University of Medical Sciences, Shiraz, Iran Hesamodin Nabavizadeh Department of Allergy and Clinical Immunology, Shiraz University of Medical Sciences, Shiraz, Iran AND Allergy Research Center, Shiraz University of Medical Sciences, Shiraz, Ira Shirin Farjadian Department of Immunology, Shiraz University of Medical Sciences, Shiraz, Iran 2021 08 03 2022 02 26 A decrease in T cell count or reduced T cell function can be indicative of T cell immunodeficiency. In the present study, T-cell function was assessed using Carboxyfluorescein diacetate succinimidyl ester (CFSE) dilution test after stimulation with commonly used Phytohaemagglutinin (PHA) or anti-CD3/anti-CD28 coated beads in pediatric patients with recurrent infections. Seven infants with recurrent infections and seven sex/age-matched healthy infants were included in this study. A blood cell count, immunophenotyping, and serum immunoglobulin level were performed. The proliferation of T cells was also assessed with CFSE dilution after stimulation with PHA or anti-CD3/anti-CD28 coated beads.  This study showed increased IgA, IgG, and IgM levels in patients compared to the controls. In contrast to the controls, the immunophenotyping results showed a significant decline in the number of CD4+ T cells in patients. Although there was no difference in CD3+ T cell proliferation between patients and controls, the CD4+ and CD8+ T cell proliferation rates were significantly decreased in patients when stimulated with PHA. As a mitogen with the potential for maximum proliferation of T cells, PHA is better able to distinguish between patients with recurrent infections and controls than anti-CD3/anti-CD28, which mimics only the TCR pathway for stimulation of T cells.  https://ijaai.tums.ac.ir/index.php/ijaai/article/view/3311 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/3311/1875