Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 23 4 2024 07 27 457 466 Esmaeil Mortaz Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran AND Clinical Tuberculosis and Epidemiology Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran Neda Dalil Roofchayee Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran AND Clinical Tuberculosis and Epidemiology Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran Hamidreza Jamaati Clinical Tuberculosis and Epidemiology Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran Mohammad Varaham Mycobacteriology Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran Zahra Abtahian Clinical Tuberculosis and Epidemiology Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran Babak Afshar Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran AND Clinical Tuberculosis and Epidemiology Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran Mahsa Rekabi Clinical Tuberculosis and Epidemiology Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran Ian Adcock National Heart and Lung Institute, Imperial College London, London, UK AND The NIHR Imperial Biomedical Research Centre, London, UK Payam Tabarsi Clinical Tuberculosis and Epidemiology Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran 2023 05 14 2023 10 09 Patients with immunodeficiency are at higher risk of severe disease and death following SARS-CoV-2 infection compared to the general population. Here, we describe humoral and cellular immune responses in 5 patients with immunodeficiency, 2 patients with multiple sclerosis, 1 patient with chronic lymphocytic leukemia (CLL), 1 patient with Good’s syndrome, and 1Human Immunodeficiency Virus (HIV) positive with developed Acquired immunodeficiency syndrome (AIDS)- patient. T-cell responses were evaluated using the QuantiFERON SARS-CoV-2 assay following incubation with the SARS-CoV-2 Ag1, Ag2, and Ag3 viral antigens. Immunophenotyping of CD4+ and CD8+ T cells and CD19+ and CD20+ B cells was determined by flow cytometry. All studied immunocompromised patients or those with acquired immune dysregulation patients showed reduced cellular immune responses (release of interferon (IFN)-g) to SARS-CoV-2 antigens than healthy controls [patients; Ag1, Ag2 and Ag3 and Nil (Median 5-95% percentile) (12 (1-95), 12 (1.5-78), 13.5 (12-95) and 3 (1-98) U/mL)], controls; Ag1, Ag2 and Ag3 and Nil (Median 5-95% percentile) 24.5 (7-89), 65 (31-173), 53.5 (13-71.5) and 3 (1-14) U/mL)]. The frequency of peripheral blood B cells was also reduced in these patients compared to healthy control subjects. T-cell-dependent antibody responses require the activation of B cells by helper T cells. Reduced B cell numbers in immunocompromised patients infected with SARS-CoV-2 indicate the need for these patients to take additional precautions to prevent COVID-19 infection. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/3835 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/3835/2062