Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 54 8 2025 09 02 1563 1576 EN Fengyu Xue 1. Department of Epidemiology and Biostatistics, School of Public Health, Jilin University, Changchun 130021, China 2. Department of Immunization and Prevention, Fangshan District Center for Disease Prevention and Control, Beijing 102488, China Zhijun Li Department of Epidemiology and Biostatistics, School of Public Health, Jilin University, Changchun 130021, China Lijuan Yan Department of Psychology, Changchun Sixth Hospital, Changchun 130000, China Qiong YU Department of Epidemiology and Biostatistics, School of Public Health, Jilin University, Changchun 130021, China Yanchi Zhang Department of Psychology, Changchun Sixth Hospital, Changchun 130000, China 2024 08 14 2025 03 09 Background: We have included literature on changes in immune cells in patients with schizophrenia and have systematically and quantitatively reviewed these studies through meta-analysis, with a view to understanding the potential effects of immune system dysfunction on the pathophysiology of schizophrenia. Methods: We conducted a systematic search in PubMed, Embase, Web of Science, and the Cochrane Library, covering publications from inception to Sep 25, 2023. The systematic review followed the PRISMA guidelines, and a random-effects meta-analysis was performed. Heterogeneity was evaluated using the I² index, and sensitivity analyses were conducted to assess the stability of the findings. Results: The systematic review includes 42 studies on schizophrenia. Meta-analysis revealed that compared to the control group, schizophrenia patients had significantly higher white blood cell counts (WBC, P<0.01), CD4 absolute values (P=0.02), CD4 percentage (CD4%, P=0.05), CD4/CD8 ratio (P<0.01), monocyte-to-lymphocyte ratio (MLR, P<0.01), neutrophil-to-lymphocyte ratio (NLR, P<0.01), and platelet-to-lymphocyte ratio (PLR, P<0.01). No significant differences were observed for other immune markers in the meta-analysis. Conclusion: The number of immune cells in the blood of patients with schizophrenia increased. Therefore, more research on immune system abnormalities in schizophrenia patients is needed to better understand the underlying mechanisms between schizophrenia and immune cell parameters. https://ijph.tums.ac.ir/index.php/ijph/article/view/36350 https://ijph.tums.ac.ir/index.php/ijph/article/download/36350/8614