Use of T-Cell Growth Factors (Interleukins 2, 4, 7, 10, and 12) in the Evaluation of T-Cell Reactivity to Melanoma

Adaptive Immunity and the Tumor Microenvironment

The adaptive immune response is a 500-million-year-old (the "Big Bang" of Immunology) collective set of rearranged and/or selected receptors capable of recognizing soluble and cell surface molecules or shape (B cells, antibody), endogenous and extracellular peptides presented by Major Histocompatibility (MHC) molecules including Class I and Class II (conventional αβ T cells), lipid in the context of MHC-like molecules of the CD1 family (NKT cells), metabolites and B7 family molecules/butyrophilins with stress factors (γδT cells), and stress ligands and absence of MHC molecules (natural killer, NK cells). What makes tumor immunogenic is the recruitment of initially innate immune cells to sites of stress or tissue damage with release of Damage-Associated Molecular Pattern (DAMP) molecules. Subsequent maintenance of a chronic inflammatory state, representing a balance between mature, normalized blood vessels, innate and adaptive immune cells and the tumor provides a complex tumor microenvironment serving as the backdrop for Darwinian selection, tumor elimination, tumor equilibrium, and ultimately tumor escape. Effective immunotherapies are still limited, given the complexities of this highly evolved and selected tumor microenvironment. Cytokine therapies and Immune Checkpoint Blockade (ICB) enable immune effector function and are largely dependent on the shape and size of the B and T cell repertoires (the "adaptome"), now accessible by Next-Generation Sequencing (NGS) and dimer-avoidance multiplexed PCR. How immune effectors access the tumor (infiltrated, immune sequestered, and immune desserts), egress and are organized within the tumor are of contemporary interest and substantial investigation.

Mutual enhancement of IL-2 and IL-7 on DNA vaccine immunogenicity mainly involves regulations on their receptor expression and receptor-expressing lymphocyte generation

Our previous study showed that IL-2 and IL-7 could mutually enhance the immunogenicity of canine parvovirus VP2 DNA vaccine, although the underlying mechanism remained unknown. Here, we used the OVA gene as a DNA vaccine in a mouse model to test their enhancement on DNA vaccine immunogenicity and to explore the molecular mechanism. Results showed that both IL-2 and IL-7 genes significantly increased the immunogenicity of OVA DNA vaccine in mice. Co-administration of IL-2 and IL-7 genes with OVA DNA significantly increased OVA-specific antibody titers, T cell proliferation and IFN-γ production compared with IL-2 or IL-7 alone, confirming that IL-2 and IL-7 mutually enhanced DNA vaccine immunogenicity. Mechanistically, we have shown that IL-2 significantly stimulated generation of IL-7 receptor-expressing lymphocytes, and that IL-7 significantly induced IL-2 receptor expression. These results contribute to an explanation of the mechanism of the mutual effects of IL-2 and IL-7 on enhancing DNA vaccine immunogenicity and provided a basis for further investigation on their mutual effects on adjuvant activity and immune regulation.

Cancer gene therapy

The prognosis of patients with some kinds of cancers whose patients are often found unresectable upon diagnosis is still dismal. In these fields, development of a new therapeutic modality is needed and gene therapy represents one promising strategy. So far, numerous cancer gene therapy clinical trials based on these principles have been carried out and have shown the safety of such modalities, but have fallen short of the initial expectations to cure cancers. In this review, we would like to make a problem-oriented discussion of current status of cancer gene therapy research by using mainly gastrointestinal cancers as an example. In order to overcome obstacles for full realization of cancer gene therapy, numerous researches have been conducted by many researchers. Various cancer-selective and non-selective genes, as well as lytic viruses themselves have been employed for gene therapy. In the context of gene delivery method, different kinds of viral and non-viral strategies have been utilized. In addition, surrogate assays, such as soluble markers and imaging, have been developed for safer and more informative clinical trials. Many experiments and clinical trials to date have figured out current obstacles for the realization of an effective cancer gene therapy modality. Tireless efforts to overcome such hurdles and continuous infusion of novel concepts into this field should lead to break through technologies and the cure of the patients.

Replication-Defective Canarypox (ALVAC) Vectors Effectively Activate Anti–Human Immunodeficiency Virus-1 Cytotoxic T Lymphocytes Present in Infected Patients: Implications for Antigen-Specific Immunotherapy

In the attempt to develop immunotherapeutic strategies for acquired immunodeficiency syndrome capable of activating effector cells in an antigen-specific manner while maintaining the broadest possible T-cell repertoire, we evaluated two canarypox (ALVAC)-based vectors for their capacity to induce ex vivo activation/expansion of human immunodeficiency virus (HIV)-specific CD8+ cytotoxic lymphocyte precursors (CTLp) obtained from HIV-1–infected donors. These two vectors, vCP205 encoding HIV-1 gp120 + TM (28 amino acid transmembrane anchor sequence) in addition to Gag/protease and vCP300 encoding gp120 + Gag/protease as well as Nef and Pol CTL determinants, are pancytotropic but replication incompetent in mammalian cells. Bulk peripheral blood mononuclear cells (PBMCs) or enriched CD8+ T cells were stimulated for 10 days with autologous ALVAC-infected PBMCs in the presence of different cytokine combinations (interleukin-2 [IL-2], IL-4, IL-7, and IL-12). Activation by ALVAC constructs was highly antigen-specific, because vCP205 elicited only Env and Gag CTL, whereas vCP300 elicited broader reactivities against Env, Gag, Pol, and Nef determinants. The ALVAC activation of CTLp was IL-2 dependent and enhanced by the addition of IL-7, whereas IL-4 and IL-12 failed to augment cytotoxic reactivities elicited by these constructs. The expansion of enriched CD8+ T cells after activation with vCP300 was higher in patients with CD4 counts greater than 400 cells/μL. Two rounds of in vitro stimulation (IVS) with vCP300 resulted in nearly an eightfold expansion of CD8+ lymphocytes over a 25-day period. After the second IVS, an average 3.2-fold increase among the different antigen-specific CTL frequencies was achieved. These studies clearly show that HIV-recombinant ALVAC vectors represent powerful polyvalent antigenic stimuli for activation and expansion of the CD8 lymphocyte response that occurs as a result of HIV infection.

Replication-Defective Canarypox (ALVAC) Vectors Effectively Activate Anti–Human Immunodeficiency Virus-1 Cytotoxic T Lymphocytes Present in Infected Patients: Implications for Antigen-Specific Immunotherapy

In the attempt to develop immunotherapeutic strategies for acquired immunodeficiency syndrome capable of activating effector cells in an antigen-specific manner while maintaining the broadest possible T-cell repertoire, we evaluated two canarypox (ALVAC)-based vectors for their capacity to induce ex vivo activation/expansion of human immunodeficiency virus (HIV)-specific CD8+ cytotoxic lymphocyte precursors (CTLp) obtained from HIV-1–infected donors. These two vectors, vCP205 encoding HIV-1 gp120 + TM (28 amino acid transmembrane anchor sequence) in addition to Gag/protease and vCP300 encoding gp120 + Gag/protease as well as Nef and Pol CTL determinants, are pancytotropic but replication incompetent in mammalian cells. Bulk peripheral blood mononuclear cells (PBMCs) or enriched CD8+ T cells were stimulated for 10 days with autologous ALVAC-infected PBMCs in the presence of different cytokine combinations (interleukin-2 [IL-2], IL-4, IL-7, and IL-12). Activation by ALVAC constructs was highly antigen-specific, because vCP205 elicited only Env and Gag CTL, whereas vCP300 elicited broader reactivities against Env, Gag, Pol, and Nef determinants. The ALVAC activation of CTLp was IL-2 dependent and enhanced by the addition of IL-7, whereas IL-4 and IL-12 failed to augment cytotoxic reactivities elicited by these constructs. The expansion of enriched CD8+ T cells after activation with vCP300 was higher in patients with CD4 counts greater than 400 cells/μL. Two rounds of in vitro stimulation (IVS) with vCP300 resulted in nearly an eightfold expansion of CD8+ lymphocytes over a 25-day period. After the second IVS, an average 3.2-fold increase among the different antigen-specific CTL frequencies was achieved. These studies clearly show that HIV-recombinant ALVAC vectors represent powerful polyvalent antigenic stimuli for activation and expansion of the CD8 lymphocyte response that occurs as a result of HIV infection.

Interleukin-7. Biology and implications for dermatology

In recent years, it has become apparent that IL-7, originally characterized as a growth factor for pre-B lymphocytes, also has important implications for the skin. Keratinocytes have been shown to produce IL-7. which in turn can elicit a variety of biological responses on several cell types residing in the skin. IL-7 has been demonstrated to augment the cytolytic activity of cytotoxic T cells (CTL) and natural killer (NK) cells against various neoplastic targets including melanoma cells. Proliferation and long-term survival of murine dendritic epidermal T lymphocytes (DETC) in vitro is supported by IL-7. IL-7 also induces secretion of inflammatory cytokines by monocytes/macrophages and renders these cells to become tumoricidal against melanoma cells. Normal and malignant melanocytes respond to IL-7 with increased expression of intercellular adhesion molecule (ICAM-1). In addition, IL-7 has been shown to act as growth factor for Sezary cells, suggesting a role of keratinocyte-derived IL-7 in the pathogenesis of cutaneous T cell lymphoma. Because of the potent in vitro immunomodulatory effects of IL-7 which have been confirmed in mouse tumor models, IL-7 may become a valuable additional agent to immunotherapeutical regimens currently studied in patients with advanced melanoma. This review summarizes our present knowledge about the molecular and immunological properties of IL7 with emphasis on the effects of that cytokine within the cutaneous compartment and the potential clinical utility in dermatology.

IL-12 gene expression in human skin-derived CD1a+ dendritic lymph cells

Recent reports point to a role for interleukin-12 (IL-12) in regulating T- and NK-cell function, macrophage activation and initiation of Th1-type cell responses. We sought to determine whether CD1a+ dendritic cells of the skin, as major antigen-presenting cells, are a source of IL-12 and therefore important in the initiation of Th1-type cell responses. To investigate this hypothesis, we cannulated microsurgically a skin-draining lymph vessel in the lower legs of five healthy volunteers. Altogether, ten different samples, each consisting of 1 x 10(6) lymph cells, were investigated. In four of the ten samples. CD1a+ dendritic lymph cells were isolated and purified by positive selection using mouse anti-CD1a monoclonal antibodies and sheep anti-mouse antibody-coated Dynabeads. Messenger RNA levels were estimated using a nested reverse transcriptase polymerase chain reaction (nRT-PCR) method. Total RNA was extracted from the cells, reverse transcribed to cDNA and amplified using specific primers for the target gene. Amplified products were sized by electrophoresis and visualized by ethidium bromide. Expression of IL-12 p40 and p35 mRNA was detected in all samples, both whole lymph samples and the highly enriched CD1a+ dendritic cell population. Our findings demonstrate that human skin-derived CD1a+ dendritic lymph cells produce IL-12 mRNA and may therefore be an important source of IL-12. Thus one might speculate that these CD1a+ dendritic cells, through their IL-12-producing capacity, might significantly influence the balance of Th1 versus Th2 reactions ultimately occurring.

IL-7 enhancement of antigen-driven activation/expansion of HIV-1-specific cytotoxic T lymphocyte precursors (CTLp)

CD8+ cytotoxic T lymphocytes are an important component in the immunologic control of human viral diseases. IL-7, a stromal cell-derived cytokine, has been demonstrated to enhance both anti-tumour and anti-viral CTL as well as lymphokine-activated killer (LAK) activity. We studied the ability of IL-7 to support the activation and the growth of in vitro antigen-specific CTL precursors (CTLp) present in peripheral blood mononuclear cells (PBMC) from HIV-infected patients. Results from these studies demonstrate that inclusion of IL-7 in a vaccinia/HIV-1 vector-based stimulation strategy greatly augmented overall CTL reactivities, whereas addition of IL-7 to unstimulated cultures failed to induce any significant anti-viral cytolytic activity. In four of six patients, HIV-specific lytic activities were significantly higher in cultures stimulated with antigen plus IL-7 compared with in vitro stimulation (IVS) with antigen alone. Cytotoxic activity was principally mediated by CD8+ effector cells, and CD3+/CD8+ cell expansion was increased by 2.7-fold in the presence of IL-7. In PBMC from seronegative donors, IL-7 enhanced anti-vaccinia CTL activities with less effect on cell proliferation. Furthermore, anti-gag CTL frequencies determined by limiting dilution analysis were increased by 2- and 10-fold in two asymptomatic patients following IVS plus IL-7 compared with antigen stimulation alone. Cytofluorimetric analysis revealed that IL-7 preferentially expanded CD8 memory cells (CD45RO+) and CD8+ lymphocytes expressing activation molecules. IL-7 was also able to support the growth of CD4+ lymphocytes, while having no effect on natural killer (NK)/K lymphocytes. Taken together, these data suggest that IL-7 acts cooperatively with the antigen supporting in vitro maturation of CTLp into functional cytotoxic effectors. Thus IL-7 may be an important biologic entity to consider as part of future immune-based therapies in which ex vivo expansion of antigen-driven CTL is an important determinant.

Freshly isolated tumour-infiltrating T-lymphocytes have a high cytotoxic potential, as measured by their ability to induce apoptosis in the target cell

To test if freshly isolated tumour-infiltrating lymphocytes (TIL) can induce apoptosis in a target cell, we have combined two previously described methods. Because TIL predominantly are T-lymphocytes, we have applied a redirected approach. When the target cells that express anti-human-CD3 monoclonal antibodies in their membranes bind to the T cell receptor-associated CD3-complex, signals are generated, which activate T cell effector mechanisms. This approach circumvents problems with MHC-restriction and allows for functional testing of all T cells, irrespective of their clonal specificity. In order to assay for induction of DNA fragmentation, we have labelled the target cell nuclei with [3H]thymidine. Upon harvesting fragmented DNA are washed away. Electrophoretic analysis of the fragmented DNA demonstrated the characteristic 'ladder' pattern, consistent with apoptosis. This rapid and simple assay monitors the capacity of different T cells to induce apoptosis in the target cell. It depends on intercellular interactions and clearly discriminates between different T cell subsets. With this assay we demonstrate the functional integrity of the cytotoxic effector arm of freshly isolated TIL.