title: Targeted delivery of anti-CTLA-4 antibody downregulates T cell function in vitro and in vivo.
abstract: CTLA-4 is a T cell surface molecule that binds to the costimulatory molecules CD80 and CD86 on antigen-presenting cells and downregulates T cell function. Therefore, we wanted to test whether antigen-specific activated T cells could be inhibited through directed CTLA-4 signaling using a bispecific antibody (BiAb) capable of simultaneously binding to CTLA-4 and a tissue-specific antigen. The BiAb was prepared by linking two separate monoclonal antibodies against CTLA-4 and the thyroid-stimulating hormone receptor (TSHR). The mouse B cell lymphoma line M12 (H2(d)) was used to induce alloreactive T cells in CBA/J mice (H2(k)); M12 cells stably transfected with the cDNA encoding murine TSHR (mM12) were used to restimulate the alloresponse in vitro. Results of assays for in vitro T cell proliferation, IL-2 production, and cytotoxicity in the presence of BiAb demonstrated that the BiAb could inhibit the T cell alloresponse when stimulated with mM12 cells but not with M12 cells. This effect was dependent on binding of TSHR-bound BiAb to CTLA-4, since the addition of soluble CTLA-4-Ig blocked the inhibitory effect. Injection of mM12 cells, along with the BiAb, not with antibodies against TSHR or CTLA-4 either separately or together, into CBA/J mice (H2(k)) downregulated alloreactive T cell responses. Our study demonstrated that the presence of CTLA-4 signaling molecules on the surface of target cells can protect those cells from immune attack by antigen-specific T cells and suggested that a similar approach could have potential therapeutic value in transplant rejection and tissue-specific autoimmune diseases.
authors.affiliation: Department of Surgery, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA.
authors.forename: S
authors.initials: S
authors.lastname: Rao
authors.forename: C
authors.initials: C
authors.lastname: Vasu
authors.forename: O
authors.initials: O
authors.lastname: Martinez
authors.forename: S
authors.initials: S
authors.lastname: Kaithamana
authors.forename: B S
authors.initials: BS
authors.lastname: Prabhakar
authors.forename: M J
authors.initials: MJ
authors.lastname: Holterman
mesh_terms: D000069594:Abatacept; D000818:Animals; D018033:Antibodies, Bispecific / Q000494:pharmacology*; D000911:Antibodies, Monoclonal / Q000494:pharmacology* / Q000627:therapeutic use; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000276:immunology*; D001327:Autoimmune Diseases / Q000628:therapy; D060908:CTLA-4 Antigen; D006224:Cricetinae; D015536:Down-Regulation; D005260:Female; D018796:Immunoconjugates; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007376:Interleukin-2 / Q000096:biosynthesis; D051379:Mice; D008807:Mice, Inbred BALB C; D008808:Mice, Inbred CBA; D009928:Organ Specificity; D011989:Receptors, Thyrotropin / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D018033:Antibodies, Bispecific; D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000943:Antigens, Differentiation; D060908:CTLA-4 Antigen; C556707:Ctla4 protein, mouse; D018796:Immunoconjugates; D007166:Immunosuppressive Agents; D007376:Interleukin-2; D011989:Receptors, Thyrotropin; D000069594:Abatacept