title: Antigen specificity of dual reactive T hybridomas determines the requirement for CD40 ligand-CD40 interactions.
abstract: CD40 ligand (CD40L) expression on T cells is known to play a crucial role in B cell responses. Some evidence also supports a role for CD40L-CD40 interactions in T cell responses, at least in vivo. Whether the T cell requirement for these interactions is an invariable finding, however, is less clear. Here, we provide evidence that the Ag specificity of T cells influences the requirement for CD40L. T cell hybridomas with dual reactivity for two different Ags, allo-H2-Ap and Mls(a) superantigens, display a differential requirement for CD40L expression. Whereas the response to splenic APC expressing Mls(a) Ags requires CD40L expression, the response to alloantigen-bearing APC does not. The requirement for CD40L expression for the Mls(a) response appears to reflect a strong dependence of this response on ICAM-1 (intercellular adhesion molecule-1) and the ability of CD40-mediated signals to regulate ICAM-1 expression. These findings demonstrate that CD40L-CD40-mediated cross-talk is important for some but not all T cell responses and is influenced by both the type of Ag recognized and the type of APC.
authors.affiliation: Department of Immunology, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Ozaki
authors.forename: L
authors.initials: L
authors.lastname: Karlsson
authors.forename: P A
authors.initials: PA
authors.lastname: Peterson
authors.forename: S R
authors.initials: SR
authors.lastname: Webb
mesh_terms: D000818:Animals; D018033:Antibodies, Bispecific / Q000276:immunology*; D000918:Antibody Specificity; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology*; D019013:CD40 Antigens / Q000276:immunology*; D023201:CD40 Ligand; D005434:Flow Cytometry; D006825:Hybridomas / Q000276:immunology*; D008562:Membrane Glycoproteins / Q000276:immunology*; D051379:Mice; D018089:Superantigens / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D018033:Antibodies, Bispecific; D000945:Antigens, Differentiation, T-Lymphocyte; D019013:CD40 Antigens; D008562:Membrane Glycoproteins; D018089:Superantigens; D023201:CD40 Ligand