Immune and TRG Repertoire Signature of the Thymus in Down Syndrome Patients
2Pediatric Cardiology Unit, Edmond and Lily Safra Children’s Hospital, Chaim Sheba Medical Center, ישראל
3Pediatric Cardiac Intensive Care Unit, Edmond and Lily Safra Children’s Hospital, Chaim Sheba Medical Center, ישראל
4Department of Pediatric Cardio-Thoracic Surgery, Edmond and Lily Safra Children’s Hospital, Chaim Sheba Medical Center, ישראל
5Sackler Faculty of Medicine, Tel Aviv University, ישראל
Background: Patients with Down syndrome are at increased risk for infections and autoimmune disorders. Abnormalities were found in several immune components. However, differences in the level of the T cell receptor repertoire have never been shown. We compared the T cell receptor gamma (TRG) repertoire of children with Down syndrome and non-syndromic children by next generation sequencing, in addition to other immune markers.
Methods: DNA was extracted from thymuses of 6 children with Down syndrome and 6 non- syndromic patients who underwent heart surgery. Peripheral blood counts and T-cell sub-populations, thymus TCR excision circles (TRECs), spectratyping and next generation sequencing for TRG were analyzed.
Results: Participants’ mean age was 7 months. Mean lymphocyte count was slightly lower in patients with Down syndrome, whereas TREC results were mostly similar (p=n.s). Furthermore, clonality was not seen in spectratyping analysis. The TRG repertoire analysis showed that patients with Down syndrome had a significantly larger number of unique TRG sequences, and a nonsignificant decrease in the total number of sequences. No remarkable differences in V and J gene usages were found.
Conclusion: Patients with Down syndrome showed increased TRG repertoire diversity and decreased clonal expansion.
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