Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 24 6 2025 10 29 760 770 Ying Cheng Department of Pediatrics, Liangxiang Hospital of Beijing Fangshan District, Beijing, China Yi Tai Department of Pediatrics, Liangxiang Hospital of Beijing Fangshan District, Beijing, China Liuyuan Ge Department of Pediatrics, Liangxiang Hospital of Beijing Fangshan District, Beijing, China Xingshuo Qiu Department of Pediatrics, Liangxiang Hospital of Beijing Fangshan District, Beijing, China Jiayin Wang Department of Pediatrics, Liangxiang Hospital of Beijing Fangshan District, Beijing, China Yujuan Chang Department of Pediatrics, Liangxiang Hospital of Beijing Fangshan District, Beijing, China 2024 11 25 2025 03 03 The objective of this study was to compare the concentrations of relative and absolute regulatory T cells (Tregs) in preterm neonates diagnosed with necrotizing enterocolitis (NEC) with those in the control group. The study consisted of 60 preterm neonates, 30 with NEC and 30 without NEC. Blood samples were obtained and processed for the enumeration of Treg cells by multiparameter flow cytometry with markers such as CD4, CD25, and FOXP3, and the activation markers CD45RA, CD45RO, HLA-DR, and CTLA-4. There were no significant differences in gestational age, body weight, Apgar score, delivery mode, or incidence of maternal infection between the NEC group and the control group. The relative Treg percentage (% of CD4+ T cells) in the NEC group was 7.5 ± 1.2%, which was significantly lower than that in the control group (9.8 ± 1.5%). Compared with that in the control group, the absolute Treg count in the NEC group showed the same trend, and the total CD4+ T-cell count decreased significantly. The percentage of naive Tregs (% of Tregs) was significantly higher, whereas those of memory Tregs (% of Tregs), Ki-67+ (% of Tregs), and CD39+ (% of Tregs) cells were significantly lower. Tregs may be activated more as the severity of NEC increases, and the elevated levels of interleukin (IL)-10 in NEC may reflect attempts at an effective anti-inflammatory response to the proinflammatory effects of IL-6 and TNF-ɑ. Treg pathways may hold promise for NEC prognosis, although additional samples should be evaluated to validate these results.   Keywords: ; ; ; ;  https://ijaai.tums.ac.ir/index.php/ijaai/article/view/4255 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/4255/2241