Two recombinant Listeria monocytogenes (rLm) strains were produced that secrete the human papilloma virus-16 (HPV-16) E7 protein expressed in HPV-16-associated cervical cancer cells. One, Lm-E7, expresses and secretes E7 protein, whereas a second, Lm-LLO-E7, secretes E7 as a fusion protein joined to a nonhemolytic listeriolysin O (LLO). Lm-LLO-E7, but not Lm-E7, induces the regression of the E7-expressing tumor, TC-1, established in syngeneic C57BL/6 mice. Both recombinant E7-expressing rLm vaccines induce measurable anti-E7 CTL responses that stain positively for H-2Db E7 tetramers. Depletion of the CD8+ T cell subset before treatment abrogates the ability of Lm-LLO-E7 to impact on tumor growth. In addition, the rLm strains induce markedly different CD4+ T cell subsets. Depletion of the CD4+ T cell subset considerably reduces the ability of Lm-LLO-E7 to eliminate established TC-1 tumors. Surprisingly, the reverse is the case for Lm-E7, which becomes an effective anti-tumor immunotherapeutic in mice lacking this T cell subset. Ab-mediated depletion of TGF-β and CD25+ cells improves the effectiveness of Lm-E7 treatment, suggesting that TGF-β and CD25+ cells are in part responsible for this suppressive response. CD4+ T cells from mice immunized with Lm-E7 are capable of suppressing the ability of Lm-LLO-E7 to induce the regression of TC-1 when transferred to tumor-bearing mice. These studies demonstrate the complexity of L. monocytogenes-mediated tumor immunotherapy targeting the human tumor Ag, HPV-16 E7.

Late-phase human T-cell lymphotropic virus

γδ T cells play uniquely important roles in stress surveillance and immunity for infections and carcinogenesis. Human γδ T cells recognize and kill transformed cells independently of human leukocyte antigen (HLA) restriction, which is an essential feature of conventional αβ T cells. Vγ9Vδ2 γδ T cells, which prevail in the peripheral blood of healthy adults, are activated by microbial or endogenous tumor-derived pyrophosphates by a mechanism dependent on butyrophilin molecules. γδ T cells expressing other T cell receptor variable genes, notably Vδ1, are more abundant in mucosal tissue. In addition to the T cell receptor, γδ T cells usually express activating natural killer (NK) receptors, such as NKp30, NKp44, or NKG2D which binds to stress-inducible surface molecules that are absent on healthy cells but are frequently expressed on malignant cells. Therefore, γδ T cells are endowed with at least two independent recognition systems to sense tumor cells and to initiate anticancer effector mechanisms, including cytokine production and cytotoxicity. In view of their HLA-independent potent antitumor activity, there has been increasing interest in translating the unique potential of γδ T cells into innovative cellular cancer immunotherapies. Here, we discuss recent developments to enhance the efficacy of γδ T cell-based immunotherapy. This includes strategies for in vivo activation and tumor-targeting of γδ T cells, the optimization of in vitro expansion protocols, and the development of gene-modified γδ T cells. It is equally important to consider potential synergisms with other therapeutic strategies, notably checkpoint inhibitors, chemotherapy, or the (local) activation of innate immunity.

In early phases of human T-cell lymphotropic virus I-induced adult T-cel luemia (ATL), the malignant cell proliferation is acted with an autocrine process Involving coordinate esso of interleukin (IL) 2 and its r or.