TCR repertoires in neonates and children with congenital heart disease prior or post-surgery involving removal of thymic tissue

Congenital heart disease (CHD) is the most common birth defect in newborns, often requiring surgical correction with thymectomy that is known to affect the T-cell pool and subsequent disease susceptibility. Studies of gamma delta T cells, which develop as ontogenetic waves, are rare in this context. Here, prenatal and postnatal gamma delta T cells were investigated in pediatric CHD patients, who underwent cardiac surgery shortly after birth. A reduced thymic activity and perturbations in postnatal-derived T cells was evident at 5 to 12 years post-surgery. Fetal-derived CD161hiNKG2Apos Vg9Vd2 T cells, which retained their functionality, showed elevated abundance. An increase of TRDJ3pos gamma delta T cell clones in pediatric CHD patients, but not in a confirmatory group of neonates prior to cardiac surgery was identified. This study provides insight into the postnatal adaptation of gamma delta T cells in relation to thymic output and identifies persistence of fetal-derived Vg9Vd2 T cells in pediatric CHD patients.