title: Characterizing T cells in SCID patients presenting with reactive or residual T lymphocytes.
abstract: BACKGROUND
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Chaim Sheba Medical Center, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel.
authors.forename: Atar
authors.initials: A
authors.lastname: Lev
authors.forename: Amos J
authors.initials: AJ
authors.lastname: Simon
authors.forename: Luba
authors.initials: L
authors.lastname: Trakhtenbrot
authors.forename: Itamar
authors.initials: I
authors.lastname: Goldstein
authors.forename: Meital
authors.initials: M
authors.lastname: Nagar
authors.forename: Polina
authors.initials: P
authors.lastname: Stepensky
authors.forename: Gideon
authors.initials: G
authors.lastname: Rechavi
authors.forename: Ninette
authors.initials: N
authors.lastname: Amariglio
authors.forename: Raz
authors.initials: R
authors.lastname: Somech
mesh_terms: D002454:Cell Differentiation / Q000276:immunology; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology; D007223:Infant; D008213:Lymphocyte Activation / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D016511:Severe Combined Immunodeficiency / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: D011948:Receptors, Antigen, T-Cell