title: Escalating regulation of 5T4-specific IFN-γ+CD4+T cells distinguishes colorectal cancer patients from healthy controls and provides a target forin vivotherapy.
abstract: The relationship between the adaptive CD4+T cell response and human cancer is unclear. The oncofetal antigen 5T4 is expressed on many human carcinomas, including colorectal cancer (CRC) cells, but has limited expression on normal tissues. We previously identified anti-5T4 CD4+T cells in a proportion of CRC patients, and we extended this study to examine whether the quality or quantity of the T cell response reflects tumor stage. An overlapping peptide library spanning 5T4 was used as a target to enumerate cognate IFN-γ+CD4+T-cells (measured as spot forming cells [SFC]/105cultured T cells) in peripheral blood-derived lymphocytes following a 12-dayin vitroculture period comparing patients pre-operatively (n = 27) to healthy controls (n = 17). Robust 5T4-specific T cell responses were present in 100% of healthy donors. There was a steady loss of T cell responses with advancing tumors with a significant negative correlation from stage I to III (P = 0.008). The predictability of the decline meant < 200 SFC/105was only found in subjects with stage III CRC. The mechanism of loss of T cell response is independent of HLA-DR type or patient age, but does correspond to increases in Foxp3+regulatory T cells (Tregs). Using low-dose cyclophosphamide to reduce the proportion of Tregsin vivoresulted in increased anti-5T4 T cell responses in CRC patients. The selective loss of 5T4-specific IFN-γ+CD4+T cell responses implies a link between tumor stage and antitumor Th1 effector function; depleting Tregs can enhance such responses.
authors.affiliation: Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, UK.
authors.forename: Martin
authors.initials: M
authors.lastname: Scurr
authors.affiliation: Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, UK.
authors.forename: Anja
authors.initials: A
authors.lastname: Bloom
authors.affiliation: Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, UK.
authors.forename: Tom
authors.initials: T
authors.lastname: Pembroke
authors.affiliation: Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, UK.
authors.forename: Rohit
authors.initials: R
authors.lastname: Srinivasan
authors.affiliation: Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, UK.
authors.forename: Clare
authors.initials: C
authors.lastname: Brown
authors.affiliation: Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, UK.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Smart
authors.affiliation: Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, UK.
authors.forename: Hayley
authors.initials: H
authors.lastname: Bridgeman
authors.affiliation: Department of Surgery, Cardiff and Vale University Health Board, University Hospital of Wales, Cardiff, UK.
authors.forename: Mike
authors.initials: M
authors.lastname: Davies
authors.affiliation: Department of Surgery, Cardiff and Vale University Health Board, University Hospital of Wales, Cardiff, UK.
authors.forename: Rachel
authors.initials: R
authors.lastname: Hargest
authors.affiliation: Department of Surgery, Cardiff and Vale University Health Board, University Hospital of Wales, Cardiff, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Phillips
authors.affiliation: Department of Histopathology, Cardiff and Vale University Health Board, University Hospital of Wales, Cardiff, UK.
authors.forename: Adam
authors.initials: A
authors.lastname: Christian
authors.affiliation: Department of Histopathology, Cardiff and Vale University Health Board, University Hospital of Wales, Cardiff, UK.
authors.forename: Tom
authors.initials: T
authors.lastname: Hockey
authors.affiliation: Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, UK.
authors.forename: Awen
authors.initials: A
authors.lastname: Gallimore
authors.affiliation: Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Godkin
keywords: 5T4; CD4+ T cells; colorectal cancer; epitopes; regulatory T cells