title: Identification of human regulatory T cells in the setting of T-cell activation and anti-CTLA-4 immunotherapy on the basis of expression of latency-associated peptide.
abstract: Effector and regulatory T cells (Treg) share multiple markers that make it difficult to discern differences in these populations in humans. The transcription factor FoxP3 has been shown to identify Tregs. However, the detection of FoxP3 requires cell permeabilization, thereby preventing isolation of viable Tregs. Subsequently, the extracellular marker CD127 was established for the identification of Tregs. However, these studies were not conducted in the setting of immunotherapy. Here, we conducted studies to analyze CD127 and FoxP3 expression on T cells before and after in vitro activation as well as in the setting of patients treated with antibodies directed against cytotoxic T-lymphocyte antigen-4 (CTLA-4). We show that latency-associated peptide (LAP), as opposed to CD127, was capable of identifying Tregs after in vitro activation as well as after treatment with anti-CTLA-4. Therefore, we propose that LAP should be used as a marker of Tregs for immune monitoring studies in patients treated with active immunotherapy such as anti-CTLA-4.
  
  
  CONCLUSIONS
  Tregs play an important role in human diseases, including cancer and autoimmunity; however, it has been difficult to study these cells because of a lack of an appropriate marker. Here, we propose LAP as a marker that can be used to identify Tregs in patients treated with immunotherapy, thereby permitting isolation of these cells for functional studies and for ex vivo expansion.
authors.affiliation: Departments of Genitourinary Medical Oncology and Immunology, The University of Texas, MD Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Sun
authors.forename: Derek Ng
authors.initials: DN
authors.lastname: Tang
authors.forename: Tihui
authors.initials: T
authors.lastname: Fu
authors.forename: Padmanee
authors.initials: P
authors.lastname: Sharma
mesh_terms: D000328:Adult; D000906:Antibodies / Q000627:therapeutic use; D060908:CTLA-4 Antigen / Q000037:antagonists & inhibitors / Q000276:immunology; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000097:blood / Q000276:immunology; D006801:Humans; D007167:Immunotherapy; D053699:Interleukin-7 Receptor alpha Subunit / Q000097:blood / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000166:cytology* / Q000276:immunology*; D001749:Urinary Bladder Neoplasms / Q000097:blood / Q000276:immunology
chemical_list: D000906:Antibodies; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D053699:Interleukin-7 Receptor alpha Subunit