Neonatal Naïve CD8+ and CD4+ T Cells Exhibit Distinct Metabolic Profiles After Activation 2309657

Abstract Introduction Neonatal immune responses differ markedly from those of adults, partly due to distinct metabolic programs within immune cells. Because cellular function is closely tied to underlying metabolic pathways, defining these early-life programs is essential for understanding age-specific immunity. We previously showed that isolated neonatal naïve CD8+ T cells have greater glycolytic capacity than adult cells. Still, it is unknown whether these differences persist when T cells are assessed directly in the more physiologic context of whole-blood—derived white blood cells. Methods We compared metabolic function of neonatal (cord blood) and adult naïve CD8+ and CD4+ T cells in activated (PMA/ionomycin) RBC-lysed white blood cells using the SCENITH (Single Cell ENergetIc metabolism by profiling Translation inHibition) assay, which quantifies reliance on glycolytic and oxidative pathways for protein (and indirectly ATP) synthesis. We also evaluated transcription factor and effector molecule expression to relate metabolic states to functional characteristics. Results Neonatal CD8+ and CD4+ T cells showed significantly lower mitochondrial dependence and higher glycolytic capacity than adult counterparts. Neonatal CD4+ T cells also demonstrated reduced glucose dependence and increased ability to use fatty acids and amino acids as alternative substrates for ATP generation. These findings indicate a more glycolytic and metabolically flexible profile in neonatal T cells. Conclusion Neonatal T cells rely more on glycolysis, less on mitochondrial respiration, and display greater flexibility in substrate use to sustain protein synthesis. Defining these age-specific metabolic programs will help distinguish normal developmental trajectories from pathogenic immune responses and may inform future age-tailored immunotherapies. Funding Source NIAID Topic Categories Immune Response Regulation: Molecular Mechanisms (IRM)