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Clinical and Developmental Immunology
Volume 2012 (2012), Article ID 261470, 9 pages
http://dx.doi.org/10.1155/2012/261470
Research Article

Characterizing T Cells in SCID Patients Presenting with Reactive or Residual T Lymphocytes

1Cancer Research Center, Chaim Sheba Medical Center, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
2Hematology Laboratory, Chaim Sheba Medical Center, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
3Pediatric Immunology Service of Edmond and Lily Safra Children’s Hospital, Chaim Sheba Medical Center, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
4Department of Pediatric Hematology-Oncology, Hadassah Medical Center, Hadassah Hebrew University, 91120 Jerusalem, Israel

Received 13 June 2012; Revised 29 July 2012; Accepted 5 August 2012

Academic Editor: George N. Goulielmos

Copyright © 2012 Atar Lev et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Introduction. Patients with severe combined immunodeficiency (SCID) may present with residual circulating T cells. While all cells are functionally deficient, resulting in high susceptibility to infections, only some of these cells are causing autoimmune symptoms. Methods. Here we compared T-cell functions including the number of circulating CD3+ T cells, in vitro responses to mitogens, T-cell receptor (TCR) repertoire, TCR excision circles (TREC) levels, and regulatory T cells (Tregs) enumeration in several immunodeficinecy subtypes, clinically presenting with nonreactive residual cells (MHC-II deficiency) or reactive cells. The latter includes patients with autoreactive clonal expanded T cell and patients with alloreactive transplacentally maternal T cells. Results. MHC-II deficient patients had slightly reduced T-cell function, normal TRECs, TCR repertoires, and normal Tregs enumeration. In contrast, patients with reactive T cells exhibited poor T-cell differentiation and activity. While the autoreactive cells displayed significantly reduced Tregs numbers, the alloreactive transplacentally acquired maternal lymphocytes had high functional Tregs. Conclusion. SCID patients presenting with circulating T cells show different patterns of T-cell activity and regulatory T cells enumeration that dictates the immunodeficient and autoimmune manifestations. We suggest that a high-tolerance capacity of the alloreactive transplacentally acquired maternal lymphocytes represents a toleration advantage, yet still associated with severe immunodeficiency.