The latent form of the dimeric transcription factor NF-kappa B is sequestered in the cytoplasm by proteins containing ankyrin repeats, such as 1 kappa B alpha and beta, or by the p105 precursor form of the NF-kappa B p50 subunit. Tumor necrosis factor alpha or virus infection can cause targeted destruction of 1 kappa B and nuclear translocation of NF-kappa B. Following translocation, NF-kappa B mediates immune, inflammatory, or anti-apoptotic responses. Here we present evidence that beginning at around 6 h postinfection, herpes simplex virus (HSV) induces a persistent translocation of NF-kappa B into the nucleus of C33 cells, coincident with loss of both 1 kappa B alpha and 1 kappa B beta. Translocation failed to occur when infecting virus was preincubated with neutralizing antibody to viral envelope glycoproteins gD or gH, thus preventing entry, or when cells infected with viruses expressing mutated forms of immediate-early regulatory proteins lCP4 or lCP27. Surprisingly, no increase in the trans-activation function of NF-kappa B, as assayed by transient expression of CAT, was detected following HSV infection. The significance of NF-kappa B nuclear translocation for virus replication was demonstrated by an 80-90% reduction in virus yield following infection of C33 cells expressing a constitutive repressor form of 1 kappa B alpha. Models that reconcile nuclear translocation of NF-kappa B with the inability to detect NF-kappa B-dependent gene expression are discussed.

Disrupting the binding of CD47 to SIRPa has emerged as a promising immunotherapeutic strategy for advanced cancers by potentiating antibody-dependent cellular phagocytosis (ADCP) of targeted antibodies. Preclinically, CD47/SIRPa blockade induces antitumor activity by increasing the phagocytosis of tumor cells by macrophages and enhancing the cross-presentation of tumor antigens to CD8 þ T cells by dendritic cells; both of these processes are potentiated by CD40 signaling. Here we generated a novel, two-sided fusion protein incorporating the extracellular domains of SIRPa and CD40L, adjoined by a central Fc domain, termed SIRPa-Fc-CD40L. SIRPa-Fc-CD40L bound CD47 and CD40 with high affinity and activated CD40 signaling in the absence of Fc receptor cross-linking. No evidence of hemolysis, hemagglutination, or thrombocytopenia was observed in vitro or in cynomolgus macaques. Murine SIRPa-Fc-CD40L outperformed CD47 blocking and CD40 agonist antibodies in murine CT26 tumor models and synergized with immune checkpoint blockade of PD-1 and CTLA4. SIRPa-Fc-CD40L activated a type I interferon response in macrophages and potentiated the activity of ADCP-competent targeted antibodies both in vitro and in vivo. These data illustrated that whereas CD47/SIRPa inhibition could potentiate tumor cell phagocytosis, CD40-mediated activation of a type I interferon response provided a bridge between macrophage-and T-cell-mediated immunity that significantly enhanced durable tumor control and rejection.

Acquired immunodeficiency syndrome (AIDS) and AIDS-related complex (ARC) are thought to be caused by human T-cell leukemia/lymphotropic virus type III (HTLV-Ill). Since (helper/inducer) lymphocytes were preferentially infected and were subjected to a characteristic cytopathic effect. The availability of multiple isolates of virus from a number of different patients and donors will greatly facilitate the characterization of HTLV-III and the study of possible biological and/or biochemical variants of the virus responsible for the development of AIDS, ARC, and related diseases.

Simultaneous blockade of immune checkpoint molecules and co-stimulation of the TNF receptor superfamily (TNFRSF) is predicted to improve overall survival in human cancer. TNFRSF co-stimulation depends upon coordinated antigen recognition through the T cell receptor followed by homotrimerization of the TNFRSF, and is most effective when these functions occur simultaneously. To address this mechanism, we developed a two-sided human fusion protein incorporating the extracellular domains (ECD) of PD-1 and OX40L, adjoined by a central Fc domain, termed PD1-Fc-OX40L. The PD-1 end of the fusion protein binds PD-L1 and PD-L2 with affinities of 2.08 and 1.76 nM, respectively, and the OX40L end binds OX40 with an affinity of 246 pM. High binding affinity on both sides of the construct translated to potent stimulation of OX40 signaling and PD1:PD-L1/L2 blockade, in multiple in vitro assays, including improved potency as compared to pembrolizumab, nivolumab, tavolixizumab and combinations of those antibodies. Furthermore, when activated human T cells were co-cultured with PD-L1 positive human tumor cells, PD1-Fc-OX40L was observed to concentrate to the immune synapse, which enhanced proliferation of T cells and production of IL-2, IFNγ and TNFα, and led to efficient killing of tumor cells. The therapeutic activity of PD1-Fc-OX40L in established murine tumors was significantly superior to either PD1 blocking, OX40 agonist, or combination antibody therapy; and required CD4+ T cells for maximum response. Importantly, all agonist functions of PD1-Fc-OX40L are independent of Fc receptor cross-linking. Collectively, these data demonstrate a highly potent fusion protein that is part of a platform, capable of providing checkpoint blockade and TNFRSF costimulation in a single molecule, which uniquely localizes TNFRSF costimulation to checkpoint ligand positive tumor cells.Electronic supplementary materialThe online version of this article (10.1186/s40425-018-0454-3) contains supplementary material, which is available to authorized users.

Vγ9Vδ2+ T cell–targeted immunotherapy is of interest to harness its MHC-independent cytotoxic potential against a variety of cancers. Recent studies have identified heterodimeric butyrophilin (BTN) 2A1 and BTN3A1 as the molecular entity providing “signal 1” to the Vγ9Vδ2 TCR, but “signal 2” costimulatory requirements remain unclear. Using a tumor cell–free assay, we demonstrated that a BTN2A1/3A1 heterodimeric fusion protein activated human Vγ9Vδ2+ T cells, but only in the presence of costimulatory signal via CD28 or NK group 2 member D. Nonetheless, addition of a bispecific γδ T cell engager BTN2A1/3A1-Fc-CD19scFv alone enhanced granzyme B–mediated killing of human CD19+ lymphoma cells when cocultured with Vγ9Vδ2+ T cells, suggesting expression of costimulatory ligand(s) on tumor cells is sufficient to satisfy the “signal 2” requirement. These results highlight the parallels of signal 1 and signal 2 requirements in αβ and γδ T cell activation and demonstrate the utility of heterodimeric BTNs to promote targeted activation of γδ T cells.