title: Alloantigenic stimulation bypasses CD28-B7 costimulatory blockade by an interleukin-2-dependent mechanism.
abstract: Allogeneic leukocytes have been used as biological adjuvants for T cell-specific responses to tumor and recall antigens, but the mechanisms underlying this effect have not been fully understood. The present study investigates whether alloantigen stimulation of human T cells would bypass an in vitro T cell costimulatory dysfunction induced by CTLA4Ig blockage of CD28-B7 interaction. Here, we demonstrate that costimulation with intact allogeneic leukocytes plus viral antigen circumvented the inhibition of this costimulatory pathway via interleukin-2 (IL-2) production, resulting in the generation of influenza-specific cytotoxic T lymphocytes (CTL). The alloantigen-induced help for influenza-specific CTL generation did not require cell-to-cell contact between responding and allogeneic stimulator cells. These results suggest that alloantigens can be used to bypass defects in the CD28-B7 costimulatory pathway and, therefore, may contribute to understanding the mechanisms of alloantigen-induced restoration of T cell-mediated immunity.
authors.affiliation: Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: V
authors.initials: V
authors.lastname: Blazevic
authors.forename: L A
authors.initials: LA
authors.lastname: Pinto
authors.forename: C M
authors.initials: CM
authors.lastname: Trubey
authors.forename: G M
authors.initials: GM
authors.lastname: Shearer
mesh_terms: D000069594:Abatacept; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000276:immunology; D018106:CD28 Antigens / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D060908:CTLA-4 Antigen; D002450:Cell Communication; D002455:Cell Division; D015793:HLA-B7 Antigen / Q000276:immunology*; D006801:Humans; D018796:Immunoconjugates; D007371:Interferon-gamma / Q000096:biosynthesis; D007376:Interleukin-2 / Q000096:biosynthesis / Q000276:immunology*; D007519:Isoantigens / Q000276:immunology*; D009975:Orthomyxoviridae / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D018106:CD28 Antigens; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; D015793:HLA-B7 Antigen; D018796:Immunoconjugates; D007376:Interleukin-2; D007519:Isoantigens; D000069594:Abatacept; D007371:Interferon-gamma