Normal neonatal TREC and KREC levels in early onset juvenile idiopathic arthritis

Objective: Dysregulated central tolerance predisposes to autoimmune diseases. Reduced thymic output as well as compromised central B cell tolerance checkpoints have been proposed in the pathogenesis of juvenile idiopathic arthritis (JIA). The aim of this study was to investigate neonatal levels of T-cell receptor excision circles (TRECs) and kappa-deleting element excision circles (KRECs), as markers of T- and B-cell output at birth, in patients with early onset JIA. Methods: TRECs and KRECs were quantitated by multiplex qPCR from dried blood spots (DBS), collected 2–5 days after birth, in 156 children with early onset JIA and in 312 matched controls. Results: When analysed from neonatal dried blood spots, the median TREC level was 78 (IQR 55–113) in JIA cases and 88 (IQR 57–117) copies/well in controls. The median KREC level was 51 (IQR 35–69) and 53 (IQR 35–74) copies/well, in JIA cases and controls, respectively. Stratification by sex and age at disease onset did not reveal any difference in the levels of TRECs and KRECs. Conclusion: T- and B-cell output at birth, as measured by TREC and KREC levels in neonatal dried blood spots, does not differ in children with early onset JIA compared to controls