title: CD45RA T-cell activation without proliferation by a partial agonist monoclonal antibody to beta1 integrin.
abstract: CD45RA T cells are fully co-activated by natural beta1 integrin ligands fibronectin (FN) and VCAM-1, as well as monoclonal antibody (mAb) 19H8, which binds a combinatorial epitope of the alpha4beta1 heterodimer. These integrin ligands stimulate CD3-dependent proliferation and the upregulation of early activation markers CD25 and CD69. However, beta1-specific antibody 33B6, which binds to a similar range of the predominant T-cell integrins as natural ligands FN (alpha4beta1 and alpha5beta1) and VCAM-1 (alpha4beta1), failed to costimulate proliferation in the CD45RA subset, while retaining the ability to costimulate early activation markers CD25 and CD69. After addition of exogenous human interleukin-2 to the culture media, 33B6 costimulation of proliferation is restored. These data provide evidence that a branch of the alpha4beta1 integrin-signaling pathway in CD45RA T cells can be independently regulated and exploited through the use of partial agonist ligands, including mAbs to the integrin heterodimer.
authors.affiliation: Department of Immunology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Billard
authors.forename: Bradley W
authors.initials: BW
authors.lastname: McIntyre
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D049109:Cell Proliferation; D006801:Humans; D019012:Integrin beta1 / Q000276:immunology*; D007376:Interleukin-2 / Q000276:immunology; D017493:Leukocyte Common Antigens / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology*; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D019012:Integrin beta1; D007376:Interleukin-2; D017493:Leukocyte Common Antigens