Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 22 2 2023 04 30 138 149 Mohammad Amin Rajizadeh Student Research Committee, Afzalipour Faculty of Medicine, Kerman University of Medical Sciences, Kerman, Iran AND Physiology Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran AND Department of Physiology and Pharmacology, Afzalpour Medical Faculty, Kerman University of Medical Sciences, Kerman, Iran Mohammad Abbas Bejeshk Physiology Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran AND Department of Physiology and Pharmacology, Afzalpour Medical Faculty, Kerman University of Medical Sciences, Kerman, Iran Amir Hossein Doustimotlagh Department of Clinical Biochemistry, Faculty of Medicine, Yasuj University of Medical Sciences, Yasuj, Iran AND Medicinal Plants Research Center, Yasuj University of Medical Sciences, Yasuj, Iran Hamid Najafipour Department of Physiology and Pharmacology, Afzalpour Medical Faculty, Kerman University of Medical Sciences, Kerman, Iran AND Cardiovascular Research Center, Institute of Basic and Clinical Physiology Sciences, Kerman University of Medical Sciences, Kerman, Iran Maryam Eftekhari Department of Genetics, Hormozgan University of Medical Science, Hormozegan, Iran Merat Mahmoodi Department of Immunology, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran Mahdokht Azizi Department of Pathology, Shahid Beheshti Hospital, Yasuj University of Medical Science, Yasuj, Iran Fahimeh Rostamabadi Department of Medical Immunology, Faculty of Medicine, Rafsanjan University of Medical Sciences, Rafsanjan, Iran AND Noncommunicable Diseases Research Center, Bam University of Medical Sciences, Bam, Iran Hossein Pourghadamyari Student Research Committee, Afzalipour Faculty of Medicine, Kerman University of Medical Sciences, Kerman, Iran ANDDepartment of Clinical Biochemistry, Afzalipour Medical Faculty, Kerman University of Medical Sciences, Kerman, Iran AND Gastroenterology and Hepatology Research Center, Institute of Basic and Clinical Physiology Sciences, Kerman University of Medical Sciences, Kerman, Iran AND Research Center for Hydatid Disease, Kerman University of Medical Sciences, Kerman, Iran 2022 10 01 2023 01 29 Asthma is an inflammatory disease of the airways. We assessed the anti-inflammatory and antioxidative impacts of quercetin, a plant derivative, on inflammatory and oxidative indices in lung tissue and serum of rats with asthma.Asth ma was induced by ovalbumin. Rats were divided into 4 groups: control, asthma+vehicle (Receieved normal saline), asthma+dexamethasone, and asthma+quercetin. After asthma induction, quercetin (50 mg/kg) and dexamethasone (2.5 mg/kg) were injected intraperitoneally once daily for 1 week. On day 50, lung histopathology indices; inflammatory factors; tissue gene expression, including GATA Binding Protein 3 (Gata-3), Tbx21 (T-bet), Transforming growth factor-β (TGF-β), Il10 (IL-10), Il1b (IL-1β), Il6 (IL-6), Acta2 (α-SMA), and Tnf (TNF-α); and oxidative stress indices (malondialdehyde [MDA], catalase [CAT], glutathione peroxidase [GPX], superoxide dismutase [SOD], and total antioxidant capacity [TAC]) in tissue and serum, were evaluated. The results showed that quercetin reduced Gata3, Tnf, Tgfb1, Il1b, and Acta2 gene expression and increased Tbx21 gene expression following asthma. Quercetin also improved oxidative stress by decreasing MDA levels and increasing TAC, CAT, SOD, and GPX levels in serum and lung tissue. Furthermore, quercetin decreased IL6 and TNFα levels and increased IL10 levels in lung tissue after asthma was treated with quercetin. Quercetin ameliorates oxidative stress and inflammation caused by asthma, especially at the tissue level. Therefore, quercetin can be considered a potent antiasthmatic agent. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/3668 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/3668/1935

Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 22 2 2023 04 30 124 137 Hua Feng School of Public Health, Nanchang University, Nanchang, Jiangxi, China AND State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi, China Yongning Wu State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi, China AND Corresponding Author, NHC Key Laboratory of Food Safety Risk Assessment, China National Center for Food Safety Risk Assessment, Beijing, China 2021 11 02 2022 11 22 The global prevalence of allergies is on the rise. Food allergies are of special concern among children under 5 years of age, leading to morbidity and mortality. Though the standard management is avoidance, probiotics are being used widely to prevent and treat food allergies. We aimed to determine the effect of probiotics as a therapeutic option for controlling food and cow’s milk allergy among children under 5 years of age. A systematic search of electronic medical literature databases was conducted. We included all eligible randomized controlled trials available from inception until May 2021. The primary outcome of interest was the relief of allergic symptoms, while the secondary outcome was the induction of tolerance. Two investigators undertook the literature search, screening, data extraction, and quality appraisal independently. Data analysis and synthesis were performed using STATA 14 software. Subgroup analysis was performed for the duration of use and follow-up, and the age category of children included in the outcome were done. Twenty trials involving 4043 pediatric patients with food allergies were included in the review. Subgroup analysis also revealed that probiotics were effective in treating food allergies across the various subgroups included in the model. Around 15 trials reported our primary outcome, relief of symptoms, as a binary variable, which was pooled to obtain a risk ratio of 0.86 (95% confidence interval [CI], 0.77–0.95), with very low heterogeneity (I2 7.7%). Six trials were included for the secondary outcome of interest, which gave an imprecise pooled estimate of 1.29 (95% CI, 0.98–1.70) with significant heterogeneity (I2 7). Thus, we conclude that probiotics can serve as a vital therapeutic option in tackling food allergies among children less than 5 years of age. Further larger studies exploring the effectiveness of individual strains and their safety pattern are essential.  https://ijaai.tums.ac.ir/index.php/ijaai/article/view/3393 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/3393/1937

Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 22 2 2023 04 30 212 216 Norio Kodaka Division of Respiratory Medicine, Department of Internal Medicine, Toho University Ohashi Medical Center, Ohashi, Meguro-ku, Tokyo, Japan Chihiro Nakano Division of Respiratory Medicine, Department of Internal Medicine, Toho University Ohashi Medical Center, Ohashi, Meguro-ku, Tokyo, Japan Takeshi Oshio Division of Respiratory Medicine, Department of Internal Medicine, Toho University Ohashi Medical Center, Ohashi, Meguro-ku, Tokyo, Japan Takatomo Hirouchi Division of Respiratory Medicine, Department of Internal Medicine, Toho University Ohashi Medical Center, Ohashi, Meguro-ku, Tokyo, Japan Yuka Yamada Division of Respiratory Medicine, Department of Internal Medicine, Toho University Ohashi Medical Center, Ohashi, Meguro-ku, Tokyo, Japan Hiroto Matsuse Division of Respiratory Medicine, Department of Internal Medicine, Toho University Ohashi Medical Center, Ohashi, Meguro-ku, Tokyo, Japan 2022 03 23 2023 03 13 No Abstract No Abstract No Abstract https://ijaai.tums.ac.ir/index.php/ijaai/article/view/3489 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/3489/1939

Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 22 2 2023 04 30 208 211 Simona Barni Allergy Unit, Meyer Children’s Hospital IRCCS, Florence, Italy Marta Vazquez-Ortiz National Heart & Lung Institute, Imperial College London, London, United Kingdom Mattia Giovannini 1 Allergy Unit, Meyer Children’s Hospital IRCCS, Florence, Italy AND Department of healt Science, University of Florence, Florence, Italy Giulia Liccioli Allergy Unit, Meyer Children’s Hospital IRCCS, Florence, Italy Lucrezia Sarti Allergy Unit, Meyer Children’s Hospital IRCCS, Florence, Italy Giulia Lascialfari Allergy Unit, Meyer Children’s Hospital IRCCS, Florence, Italy Laura Pisano Immunology and Molecular Microbiology Unit, Meyer Children's Hospital IRCCS, Florence, Italy Silvia Boscia Immunology and Molecular Microbiology Unit, Meyer Children's Hospital IRCCS, Florence, Italy Francesca Mori Allergy Unit, Meyer Children’s Hospital IRCCS, Florence, Italy 2022 06 07 2023 03 13 Shellfish is defined as any edible marine invertebrate and refers to crustaceans and mollusks. Crustaceans belong to the phylum Arthropods. Mollusks belong to the phylum Mollusca. This report illustrates a rare case of a 6-year-old girl with challenge-proven acute food protein–induced enterocolitis syndrome (FPIES) to cuttlefish (phylum Mollusca, class Cephalopoda), anaphylaxis to crustaceans (phylum Arthropoda), and tolerance to other mollusks, including clams and mussels (phylum Mollusca, class Bivalvia). The association of IgE-mediated food allergy and acute FPIES seen in this case is rare. To our knowledge, this is the first case of FPIES to cuttlefish reported in a child. This challenge highlights the need for further research into the allergens and mechanisms underpinning FPIES at a molecular level, enabling a better understanding of cross-reactivity patterns and the development of diagnostic and predictive tests to assist in clinical practice. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/3566 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/3566/1940

Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 22 2 2023 04 30 150 162 EN Shadi Paydarfar Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran Mohammad Amin Abbasi Firoozabadi Hospital Clinical Research Development Unit (FHCRDU), School of Medicine, Iran University Medical Science (IUMS), Tehran, Iran Ali Hashemi Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran Sodabe Taheri Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran Mojgan Bandehpour Cellular and Molecular Biology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran AND Department of Medical Biotechnology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran Nariman Mosaffa Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran 2022 03 01 2022 10 25 Extensively drug-resistant Acinetobacter baumannii is considered one of the most dangerous threats to global health, requiring novel therapeutic interventions. The outer membrane protein A (OmpA) is an immunogenic agent that triggers immune responses. The current study evaluated serum antibody levels against previously determined immunogenic OmpA peptides from A baumannii in ICU staff. Serum samples were collected from 62 ICU staff members (representing the exposed group), healthy controls (representing the nonexposed group), and patients with systemic lupus erythematosus (SLE) (as controls for nonspecific antibody reactions). After excluding the cross-reactive antibodies via Escherichia coli lysate pretreatment, all the samples were assessed in the vicinity of A baumannii lysate by enzyme-linked immunosorbent assay (ELISA). All the positive samples were assessed for interaction with previously designed and selected peptides using ELISA. The protective potential of positive serum antibodies was surveyed in vitro using an opsonophagocytic study. The most antibody positive samples against one of the dominant peptides were determined in the ICU personnel (75%).  SLE serum samples did not react with candidate peptides. The strongest positive reaction was observed in serum treatment with one of the OmpA peptides (No. 5) with significant differences compared to other designed peptides. Our findings showed that ICU samples have substantially higher antibody levels than the nonexposed group; Positive samples show strong results in the opsonophagocytosiis assay. This study demonstrates A baumannii colonization at human mucosal surfaces, especially in exposed healthy workers. Novel OmpA-derived peptides could be used to identify immunogenic vaccine candidates. Therefore, more studies are needed  before this peptide and antibody levels are used in diagnosis, prevention, or treatment.   https://ijaai.tums.ac.ir/index.php/ijaai/article/view/3473 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/3473/1932

Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 22 2 2023 04 30 172 182 EN Elham Shokati Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran AND Immunology Research Center, Iran University of Medical Sciences, Tehran, Iran Morteza Motallebnezhad Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran AND Immunology Research Center, Iran University of Medical Sciences, Tehran, Iran Elaheh Safari Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran AND Immunology Research Center, Iran University of Medical Sciences, Tehran, Iran 2022 08 22 2023 01 09 Astragalus polysaccharide (APS) is a functional component of Astragalus membranaceus with antitumor and immunomodulatory properties. This study evaluated the effect of APS on the peripheral blood mononuclear cell (PBMC) proliferation, cytokine secretion, and regulatory T cell (Treg) induction in an in vitro coculture model of human PBMCs and A2780 human ovarian cancer cells. PBMC proliferation and Treg frequency were measured by flow cytometry. Cytokine levels were assessed by enzyme-linked immunosorbent assay. APS significantly enhanced the PBMC proliferation, reduced Treg frequency, decreased anti-inflammatory cytokines including interleukin [IL]-10, transforming growth factor beta (TGF-β), and vascular endothelial growth factor-A (VEGF-A), and increased the pro-inflammatory cytokine IL-6. These findings suggest that APS may be an effective immunomodulatory supplement for cancer therapy, particularly for ovarian cancer by enhancing antitumor immune responses. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/3638 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/3638/1943

Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 22 2 2023 04 30 183 189 Maryam Rahimi Khorashad Allergy Research Center, Mashhad University of Medical Sciences, Mashhad, Iran Mohsen Ghoryani Department of Laboratory Sciences, School of Paramedical Sciences, Torbat Heydariyeh University of Medical Sciences, Torbat Heydariyeh, Iran AND Research Center of Advanced Technologies in Medicine, Torbat Heydariyeh University of Medical Sciences, Torbat Heydariyeh, Iran Arezoo Gowhari Shabgah School of Medicine, Bam University of Medical Sciences, Bam, Iran Zhaleh Shariati-Sarabi Rheumatic Diseases Research Center, Mashhad University of Medical Sciences, Mashhad, Iran AND Department of Internal Medicine, Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, Iran Jalil Tavakkol Afshari Immunology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran Mojgan Mohammadi Immunology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran 2022 08 17 2022 12 25 The therapeutic and immunomodulatory potential of mesenchymal stem cells (MSCs) in rheumatoid arthritis (RA) has attracted considerable scientific attention in recent decades. This study aimed to evaluate the expression of genes encoding interleukin (IL)4 and IL10, as well as interferon-gamma (IFNG) and transforming growth factor beta (TGFB1) in refractory RA patients following intravenous injection of autologous bone marrow-derived MSCs (BM-MSCs). This study was registered in Iranian Registry of Clinical Trials (IRCT) (2015102824760N1) and ClinicalTrials.gov (identifier: NCT03333681). Blood samples were taken from 13 patients before and 1 and 6 months after the MSC injection to evaluate the clinical manifestations, paraclinical factors, and expression of IL4, IL10, IFNG, and TGFB1 genes employing the SYBR Green real-time reverse-transcriptase polymerase chain reaction (RT-PCR) technique. There was a significant increase in the expression of TGFB1 at 1 and 6 months after the MSC injection compared to that in the baseline, while the expression of IL4 and IL10 did not change significantly. On the other hand, the expression of IFNG increased significantly after 1 month but decreased significantly at 6 months compared to 1 month after the intervention. Nevertheless, it showed no significant decrease compared to the baseline. A significant decrease was observed for the expression of IFNG 6 months after the injection compared to that after 1 month, which was in concordance with the rise in the expression of the TGFB1 gene. A significant change in the gene expression of TGFB1 and IFNG in our study was consistent with the amelioration of clinical manifestations, suggesting a mechanism of action for MSCs in the treatment of RA. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/3633 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/3633/1936

Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 22 2 2023 04 30 190 199 Marjan Taherian Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran AND Immunology Research Center, Institute of Immunology and Infectious Diseases, Iran University of Medical Sciences, Tehran, Iran Paria Bayati Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran AND Immunology Research Center, Institute of Immunology and Infectious Diseases, Iran University of Medical Sciences, Tehran, Iran Mohammad-Ali Assarehzadegan Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran AND Immunology Research Center, Institute of Immunology and Infectious Diseases, Iran University of Medical Sciences, Tehran, Iran Mansoureh Soleimani The Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran Hadi Poormoghim Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran AND Immunology Research Center, Institute of Immunology and Infectious Diseases, Iran University of Medical Sciences, Tehran, Iran Nazanin Mojtabavi Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran AND Immunology Research Center, Institute of Immunology and Infectious Diseases, Iran University of Medical Sciences, Tehran, Iran 2022 09 26 2023 01 03 The pathogenesis of idiopathic pulmonary fibrosis (IPF) is quite similar to that of cancer pathogenesis, and several pathways appear to be involved in both disorders. The mammalian target of the rapamycin (mTOR) pathway harbors several established oncogenes and tumor suppressors. The same signaling molecules and growth factors, such as vascular endothelial growth factor (VEGF), contributing to cancer development and progression play a part in fibroblast proliferation, myofibroblast differentiation, and the production of extracellular matrix in IPF development as well. The expression of candidate genes acting upstream and downstream of mTORC1, as well as Vegf and low-density lipoprotein receptor related protein 1(Lrp1), was assessed using specific primers and quantitative polymerase chain reaction (qPCR) within the lung tissues of bleomycin (BLM)-induced IPF mouse models. Lung fibrosis was evaluated by histological examinations and hydroxyproline colorimetric assay. BLM-exposed mice developed lung injuries characterized by inflammatory manifestations and fibrotic features, along with higher levels of collagen and hydroxyproline. Gene expression analyses indicated a significant elevation of regulatory associated protein of mTOR (Raptor), Ras homolog enriched in brain (Rheb), S6 kinase 1, and Eukaryotic translation initiation factor 4E-binding protein 1 (4Ebp1), as well as a significant reduction of Vegfa, Tuberous sclerosis complex (Tsc2), and Lrp1; no changes were observed in the Tsc1 mRNA level. Our findings support the elevation of S6K1 and 4EBP1 in response to the TSC/RHEB/mTORC1 axis, which profoundly encourages the development and establishment of IPF and cancer. In addition, this study suggests a possible preventive role for VEGF-A and LRP1 in the development of IPF.  https://ijaai.tums.ac.ir/index.php/ijaai/article/view/3663 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/3663/1933

Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 22 2 2023 04 30 200 207 EN Laya Kafami Psychosomatic Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran Sara Assadiasl Molecular Immunology Research Center, Tehran University of Medical Sciences, Tehran, Iran Sara Hashempour Psychosomatic Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran AND Department of Psychosomatic Medicine, Imam Khomeini Hospital Complex, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Mohammad Hossein Niknam Molecular Immunology Research Center, Tehran University of Medical Sciences, Tehran, Iran Bahareh Mohebbi Molecular Immunology Research Center, Tehran University of Medical Sciences, Tehran, Iran Mohammad Amin Hashemnezhad School of Medicine, Alborz University of Medical Sciences, Karaj, Iran Bita Ansaripour Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Arash Mirabzadeh Social Determinants of Health Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran AND Department of Psychiatry, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran Banafsheh Mosharmovahed Department of Chemical Engineering-Pharmaceutical Engineering, University of Tehran, Tehran, Iran Fateme Fazli Molecular Immunology Research Center, Tehran University of Medical Sciences, Tehran, Iran Mahshid Saleh School of Advanced Medicine, Tehran University of Medical Sciences, Tehran, Iran Nam i Mohammadian Khanssari School of Medicine, Alborz University of Medical Sciences, Karaj, Iran Ahmad Ali Noorbala Psychosomatic Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran AND Department of Psychosomatic Medicine, Imam Khomeini Hospital Complex, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran 2022 10 24 2022 10 24 Depression is one of the current dilemmas in both developed and developing societies. Studies show that the severity of psychiatric symptoms is directly related to the degree of inflammation caused by cytokines secreted by the immune system. Hence, evaluating serum cytokine levels in patients with depression can help to understand the pathogenesis of the disease and make the best therapeutic decisions. The present study investigated the levels of inflammatory cytokines, tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1), and interleukin-6 (IL-6) in patients with major depression or bipolar disorder during depressive episodes (BDDE) before and after a 6-month pharmaceutical intervention. Patients referring to 3 clinics were recruited for the study. The diagnosis of major depression or bipolar disorder in a depressive phase was made according to the Diagnostic and Statistical Manual of Mental Disorders -5(DSM-5) criteria. There was a significant difference in depression levels between the pre-intervention and 6-month follow-up in both groups. After 6 months, IL-1 and IL-6 levels in the bipolar disorder group had decreased while TNF-α levels had increased. There was also a significant difference between pre-intervention and follow-up levels of IL-1.  Serum levels of IL-1 and IL-6 decreased significantly in both groups after the 6-month follow-up, and symptom improvement was observed. TNF-α levels, on the other hand, decreased in the major depression group but increased in the bipolar disorder group. Considering that inflammation is a major outcome of depression, treatment strategies to reduce inflammation could be a practical approach to improving psychiatric symptoms. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/3672 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/3672/1931

Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 22 2 2023 04 30 163 171 EN Fateme Khani Chamani Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran Mahdi Shabani Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran Afshin Moradi Department of Pathology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran Maedeh Alinejad Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran Seyed Amir Jalali Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran 2022 05 21 2023 02 15 The effects of radiation therapy (RT) for cancer can be systemic and partially mediated by the immune system. However, radiation alone is unlikely to transform an immunosuppressive environment into an immunostimulatory one. Therefore, an effective combination of RT and immunotherapy may provide a new, more efficient treatment approach. Here, we investigated how the expression of programmed cell death-ligand 1 (PD-L1) in the tumor microenvironment varied in different RT regimens with the same biologically effective dose. In this study, female BALB/c mice inoculated with CT26 tumor cells were irradiated with 3 different RT regimens using the same BED of 40 gray (Gy). These included ablative RT (1*15 Gy), hypo-fractionated RT (2*10 Gy), and conventional (Hyper-fractionated) RT (10*3 Gy). PD-L1 expression was analyzed with immunohistochemical staining on days 2 and 20 and when the size of tumors had reached 2 cm2 after RT. All treated groups expressed PD-L1, but the group receiving single ablative high-dose RT showed higher expression compared to the other groups. No significant differences in PD-L1 expression were observed at different times in the same group. These findings showed that different regimens of RT have different effects on the TME, so a combination of RT and immune checkpoint blockade could be clinically used in cancer patients. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/3534 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/3534/1941