title: B7-CTLA4 interaction enhances both production of antitumor cytotoxic T lymphocytes and resistance to tumor challenge.
abstract: Expression of B7-family costimulatory molecules CD80 (B7-1) and CD86 (B7-2) on tumor cells enhances host immunity. However, the role of the two B7 receptors, CD28 and CTLA4 (CD152), on T cells in antitumor immune response has not been clearly elucidated. Based on the effects of anti-CD28 and anti-CTLA4 mAbs on T cell response, it was proposed that CD28-B7 interaction promotes antitumor immunity, whereas B7-CTLA4 interaction down-regulates it. A critical test for the hypothesis is whether selective engagement of CTLA4 receptors by their natural ligands CD80 and CD86 enhances or reduces antitumor immunity. Here we used tumors expressing wild-type and mutant CD80, as well as mice with targeted mutation of CD28, to address this issue. We report that in syngeneic wild-type mice, B7W (W88>A), a CD80 mutant that has lost binding to CD28 but retained binding to CTLA4, can enhance the induction of antitumor cytotoxic T lymphocytes (CTL); B7Y (Y201>A), which binds neither CD28 nor CTLA4, fails to do so. Consistent with these observations, B7W-transfected J558 plasmocytoma and EL4 thymoma grow significantly more slowly than those transfected with either vector alone or with B7Y. Optimal tumor rejection requires wild-type CD80. Moreover, expression of a high level of CD80 on thymoma EL4 cells conveys immunity in mice with a targeted mutation of CD28 gene. Taken together, our results demonstrate that B7-CTLA4 interaction enhances production of antitumor CTL and resistance to tumor challenge and that optimal enhancement of antitumor immunity by CD80 requires its engagement of both CD28 and CTLA4.
authors.affiliation: Michael Heidelberger Division of Immunology, Department of Pathology and Kaplan Comprehensive Cancer Center, New York University Medical Center, New York, NY 10016, USA.
authors.forename: P
authors.initials: P
authors.lastname: Zheng
authors.forename: Y
authors.initials: Y
authors.lastname: Wu
authors.forename: Y
authors.initials: Y
authors.lastname: Guo
authors.forename: C
authors.initials: C
authors.lastname: Lee
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000069594:Abatacept; D000818:Animals; D015703:Antigens, CD / Q000276:immunology*; D000943:Antigens, Differentiation / Q000276:immunology*; D018122:B7-1 Antigen / Q000276:immunology*; D051940:B7-2 Antigen; D060908:CTLA-4 Antigen; D007111:Immunity, Cellular; D018796:Immunoconjugates; D008297:Male; D008562:Membrane Glycoproteins / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D015398:Signal Transduction / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D018122:B7-1 Antigen; D051940:B7-2 Antigen; D060908:CTLA-4 Antigen; C497965:Cd86 protein, mouse; C556707:Ctla4 protein, mouse; D018796:Immunoconjugates; D008562:Membrane Glycoproteins; D000069594:Abatacept