CD137 promotes proliferation and survival of human B cells

CD137 (4-1BB)-mediated costimulation plays an important role in directing the fate of Ag-stimulated T cells and NK cells, yet the role of CD137 in mediating B cell function is unknown. We found that CD137 is expressed in vitro on anti-Ig–stimulated peripheral blood B cells and in vivo on tonsillar B cells with an activated phenotype. In vitro CD137 expression is enhanced by CD40 stimulation and IFN-g and is inhibited by IL-4, -10, and -21. The expression of CD137 on activated human B cells is functionally relevant because engagement with its ligand at the time of activation stimulates B cell proliferation, enhances B cell survival, and induces secretion of TNF-a and -b. Our study suggests that CD137 costimulation may play a role in defining the fate of Agstimulated human B cells.Fil: Zhang, Xiaoyu. University of Maryland; Estados UnidosFil: Voskens, Caroline J.. University of Maryland; Estados UnidosFil: Sallin, Michelle. University of Maryland; Estados UnidosFil: Maniar, Amudhan. University of Maryland; Estados UnidosFil: Montes, Carolina Lucia. University of Maryland; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; ArgentinaFil: Zhang, Yue. University of Maryland; Estados UnidosFil: Lin, Wei. University of Maryland; Estados UnidosFil: Li, Guoyan. University of Maryland; Estados UnidosFil: Burch, Erin. University of Maryland; Estados UnidosFil: Tan, Ming. University of Maryland; Estados UnidosFil: Hertzano, Ronna. University of Maryland; Estados UnidosFil: Chapoval, Andrei I.. University of Maryland; Estados UnidosFil: Tamada, Koji. University of Maryland; Estados UnidosFil: Gastman, Brian R.. University of Maryland; Estados UnidosFil: Schulze, Dan H.. University of Maryland; Estados UnidosFil: Strome, Scott E.. University of Maryland; Estados Unido

Human γδ T lymphocytes induce robust NK cell–mediated antitumor cytotoxicity through CD137 engagement

Natural killer (NK) cells are innate effector lymphocytes that control the growth of major histocompatibility complex class I negative tumors. We show here that γδ T lymphocytes, expanded in vitro in the presence isopentenylpyrophosphate (IPP), induce NK cell–mediated killing of tumors that are usually resistant to NK cytolysis. The induction of cytotoxicity toward these resistant tumors requires priming of NK cells by immobilized human immunoglobulin G1 and costimulation through CD137L expressed on activated γδ T lymphocytes. This costimulation increases NKG2D expression on the NK-cell surface, which is directly responsible for tumor cell lysis. Moreover, culturing peripheral blood mononuclear cells with zoledronic acid, a γδ T lymphocyte activating agent, enhances NK-cell direct cytotoxicity and antibody-dependent cellular cytotoxicity against hematopoietic and nonhematopoietic tumors. Our data reveal a novel function of human γδ T lymphocytes in the regulation of NK cell–mediated cytotoxicity and provide rationale for the use of strategies to manipulate the CD137 pathway to augment innate antitumor immunity