Effector Functions and Memory Accumulation of T Cells in Children with Congenital Heart Disease

All articles of this category (opens in new window) Background: Congenital heart disease (CHD) is a major global health problem. Although treatment and survival rates have impressively improved, many patients face comorbidities such as increased susceptibility to infections. As many children undergo cardiac surgery with concomitant thymectomy to ensure adequate surgical access early in life, most studies of the immune system in patients with CHD have focused on the quantitative analysis of lymphocyte subpopulations, maturation, and T cell receptor repertoires. However, knowledge of effector functions is limited. Methods: We analyzed αβ and γδ T cell phenotypes, transcriptomes, and functions in n = 16 school-age children with a wide spectrum of CHD (simple and complex TGA, DORV, TOF, VSD) who underwent cardiac surgery within the 1st year of life in comparison to age-matched healthy controls. Results: Children with CHD showed immunological alterations, including reduced T cell populations, lower CD4+ or CD8+ T cell proportions, reduced proportions of recent thymic emigrants (RTEs) and naive cells, and an accumulation of memory T cell populations in the αβ T cell compartment. There was also a reduction in the postnatally derived Vδ1 T cells and higher proportions of fetal-thymus-derived Vγ9Vδ2 T among the γδ T cells, which are one of the dominant T cells in the early fetal human thymus. Single-cell transcriptomics and functional assays revealed high activation states of T cells and higher granzyme and effector cytokine production in children with CHD, contributing to a low-grade inflammatory state. Conclusion: Our study reveals persistent alterations in T cell immunity in school-age children with CHD who underwent early-life cardiac surgery with concomitant thymectomy. These findings highlight the need for long-term immune monitoring and provide a basis for understanding immune-related comorbidities in this patient population. Publication History Article published online: 17 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany