Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 0 0 2025 12 05 1 10 Huadong Zeng Department of Respiratory and Critical Care Medicine, Shenzhen Hospital of Southern Medical University, Shenzhen, China Xuan Huang Department of Respiratory and Critical Care Medicine, Shenzhen Hospital of Southern Medical University, Shenzhen, China Guansheng Zeng Department of Respiratory and Critical Care Medicine, Shenzhen Hospital of Southern Medical University, Shenzhen, China Xian Qiu Health Management Center, Southern University of Science and Technology Hospital, Shenzhen, China Xiaoli Li Department of Respiratory and Critical Care Medicine, Shenzhen Hospital of Southern Medical University, Shenzhen, China Dandan Zhang Department of Respiratory and Critical Care Medicine, Shenzhen Hospital of Southern Medical University, Shenzhen, China Shaoqiang Zheng Department of Respiratory Medicine, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China 2025 02 11 2025 08 31 T helper 1 (TH1) and T helper 2 (TH2) cells can secrete various proinflammatory and anti-inflammatory factors, which can serve as indicators for predicting the severity of pneumonia. However, they are rarely used in combination with procalcitonin (PCT) and high-sensitivity C-reactive protein (hsCRP) detection to predict the severity of pneumonia. The purpose of this study is to investigate the combination of serum TH1/TH2 cytokines, PCT, and hsCRP for predicting the severity of community-acquired pneumonia (CAP). This study observed 58 inpatients with CAP. Analyses were conducted on the serum levels of TH1/TH2 cytokines, PCT, and hsCRP; imaging examination results; underlying diseases; pathogens; and the pneumonia severity index (PSI). The severe pneumonia group showed significantly higher PSI scores, age, and complication rates. Serum IL-2 was notably elevated in severe cases, while a combination of PCT, IL-4, TNF-α, and IFN-γ effectively predicted severe pneumonia, with an AUC of 0.712. Specific alterations in cytokines and biomarkers were identified as risk factors for higher PSI, complications, and prolonged hospitalization. The combined detection of PCT, IL-4, TNF-α, and IFN-γ provides a potential tool for predicting severe CAP, and distinct biomarker profiles are associated with different clinical outcomes. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/4340 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/4340/2268