B7S1, a novel B7 family member that negatively regulates T cell activation

Immunity. 2003 Jun;18(6):863-73. doi: 10.1016/s1074-7613(03)00147-x.


T cell activation by antigen-presenting cells (APC) is regulated by positive and negative costimulatory molecules in the B7 family. Here we describe a novel addition in this family, designated as B7S1, which is uniquely anchored to the cell membrane via a GPI linkage. B7S1 is expressed on professional APC and widely distributed in nonlymphoid tissues. A soluble B7S1-Ig fusion protein binds to activated but not naive T cells. B7S1-Ig inhibits T cell activation and IL-2 production. A monoclonal antibody that blocks binding of B7S1 to its receptor enhances T cell proliferation in vitro and exacerbates experimental autoimmune encephalomyelitis in vivo. This study identifies a novel negative regulator of T cell activation and further reveals complex costimulatory regulation of immune responses.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • B7-1 Antigen / genetics
  • B7-1 Antigen / immunology*
  • B7-1 Antigen / metabolism
  • Humans
  • Immunoglobulins / genetics
  • Immunoglobulins / metabolism
  • Lymphocyte Activation*
  • Mice
  • Molecular Sequence Data
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • T-Lymphocytes / immunology
  • T-Lymphocytes / metabolism*
  • V-Set Domain-Containing T-Cell Activation Inhibitor 1


  • B7-1 Antigen
  • Immunoglobulins
  • Recombinant Fusion Proteins
  • V-Set Domain-Containing T-Cell Activation Inhibitor 1
  • VTCN1 protein, human
  • Vtcn1 protein, mouse