Phase II trial of ipilimumab in melanoma patients with preexisting humoural immune response to NY-ESO-1.

BACKGROUND: Immune checkpoint therapy has dramatically changed treatment options in patients with metastatic melanoma. However, a relevant part of patients still does not respond to treatment. Data regarding the prognostic or predictive significance of preexisting immune responses against tumour antigens are conflicting. Retrospective data suggested a higher clinical benefit of ipilimumab in melanoma patients with preexisting NY-ESO-1-specific immunity. PATIENTS AND METHODS: Twenty-five patients with previously untreated or treated metastatic melanoma and preexisting humoural immune response against NY-ESO-1 received ipilimumab at a dose of 10 mg/kg in week 1, 4, 7, 10 followed by 3-month maintenance treatment for a maximum of 48 weeks. Primary endpoint was the disease control rate (irCR, irPR or irSD) according to immune-related response criteria (irRC). Secondary endpoints included the disease control rate according to RECIST criteria, progression-free survival and overall survival (OS). Humoural and cellular immune responses against NY-ESO-1 were analysed from blood samples. RESULTS: Disease control rate according to irRC was 52%, irPR was observed in 36% of patients. Progression-free survival according to irRC was 7.8 months, according to RECIST criteria it was 2.9 months. Median OS was 22.7 months; the corresponding 1-year survival rate was 66.8%. Treatment-related grade 3 AEs occurred in 36% with no grade 4-5 AEs. No clear association was found between the presence of NY-ESO-1-specific cellular or humoural immune responses and clinical activity. CONCLUSION: Ipilimumab demonstrated clinically relevant activity within this biomarker-defined population. NY-ESO-1 positivity, as a surrogate for a preexisting immune response against tumour antigens, might help identifying patients with a superior outcome from immune checkpoint blockade. CLINICAL TRIAL INFORMATION: NCT01216696.

In Vivo Development of Transplant Arteriosclerosis in Humanized Mice Reflects Alloantigen Recognition and Peripheral Treg Phenotype of Lung Transplant Recipients.

Experimentally, regulatory T cells inhibit rejection. In clinical transplantations, however, it is not known whether T cell regulation is the cause for, or an epiphenomenon of, long-term allograft survival. Here, we study naïve and alloantigen-primed T cell responses of clinical lung transplant recipients in humanized mice. The pericardiophrenic artery procured from human lung grafts was implanted into the aorta of NODrag-/- /IL-2rγc-/- mice reconstituted with peripheral blood mononuclear cells (PBMCs) from the respective lung recipient. Naïve or primed allogeneic PBMCs procured 21 days post-lung transplantation with or without enriching for CD4+ CD25high T cells were used. Transplant arteriosclerosis was assessed 28 days later by histology. Mice reconstituted with alloantigen-primed PBMCs showed significantly more severe transplant arteriosclerosis than did mice with naïve PBMCs (p = 0.005). Transplant arteriosclerosis was equally suppressed by enriching for autologous naïve (p = 0.012) or alloantigen-primed regulatory T cells (Tregs) (p = 0.009). Alloantigen priming in clinical lung recipients can be adoptively transferred into a humanized mouse model. Transplant arteriosclerosis elicited by naïve or alloantigen-primed PBMCs can be similarly controlled by potent autologous Tregs. Cellular therapy with expanded autologous Tregs in lung transplantation might be a promising future strategy.

Cross-genotype-specific T-cell responses in acute hepatitis E virus (HEV) infection.

Hepatitis E is an inflammatory liver disease caused by infection with the hepatitis E virus (HEV). In tropical regions, HEV is highly endemic and predominantly mediated by HEV genotypes 1 and 2 with >3 million symptomatic cases per year and around 70 000 deaths. In Europe and America, the zoonotic HEV genotypes 3 and 4 have been reported with continues increasing new infections per year. So far, little is known about T-cell responses during acute HEV genotype 3 infection. Therefore, we did a comprehensive study investigating HEV-specific T-cell responses using genotypes 3- and 1-specific overlapping peptides. Additional cytokines and chemokines were measured in the plasma. In four patients, longitudinal studies were performed. Broad functional HEV-specific CD4(+) and CD8(+) T-cell responses were detectable in patients acutely infected with HEV genotype 3. Elevated of pro- and anti-inflammatory cytokine levels during acute HEV infection correlated with ALT levels. Memory HEV-specific T-cell responses were detectable up to >1.5 years upon infection. Importantly, cross-genotype HEV-specific T-cell responses (between genotypes 1 and 3) were measurable in all investigated patients. In conclusion, we could show for the first time HEV-specific T-cell responses during and after acute HEV genotype 3 infection. Our data of cross-genotype HEV-specific T-cell responses might suggest a potential role in cross-genotype-specific protection between HEV genotypes 1 and 3.

Augmentation of Transient Donor Cell Chimerism and Alloantigen-Specific Regulation of Lung Transplants in Miniature Swine.

Donor alloantigen infusion induces T cell regulation and transplant tolerance in small animals. Here, we study donor splenocyte infusion in a large animal model of pulmonary transplantation. Major histocompatibility complex-mismatched single lung transplantation was performed in 28 minipigs followed by a 28-day course of methylprednisolone and tacrolimus. Some animals received a perioperative donor or third party splenocyte infusion, with or without low-dose irradiation (IRR) before surgery. Graft survival was significantly prolonged in animals receiving both donor splenocytes and IRR compared with controls with either donor splenocytes or IRR only. In animals with donor splenocytes and IRR, increased donor cell chimerism and CD4(+) CD25(high+) T cell frequencies were detected in peripheral blood associated with decreased interferon-γ production of leukocytes. Secondary third-party kidney transplants more than 2 years after pulmonary transplantation were acutely rejected despite maintained tolerance of the lung allografts. As a cellular control, additional animals received third-party splenocytes or donor splenocyte protein extracts. While animals treated with third-party splenocytes showed significant graft survival prolongation, the subcellular antigen infusion showed no such effect. In conclusion, minipigs conditioned with preoperative IRR and donor, or third-party, splenocyte infusions may develop long-term donor-specific pulmonary allograft survival in the presence of high levels of circulating regulatory T cells.

Stromal cells as trend-setters for cells migrating into the lymph node.

Lymph node stromal cells are known to be immunorelevant during inflammation and tolerance. Differences between peripheral lymph nodes and mesenteric lymph nodes are important for an efficient and effective immune defense. Stromal cells were considered to be perfectly adapted to their draining area and not changeable concerning their expression pattern. Here we show that stromal cells can change their profile after isolation and transplantation into a different draining area. Subsequently, these newly organized lymph nodes are able to induce not only a region-specific but also an antigen-specific immune response. Thus, stromal cells are trend-setters for immune cells in producing a microenvironment that allows an optimized immune defense.

Naive tumour-specific CD4+ T cells were efficiently primed in acute lymphoblastic leukaemia.

The recognition and neutralization of tumour cells is one of the big challenges in immunity. The immune system has to recognize syngeneic tumour cells and has to be primed and respond in an adequate manner. Priming of a leukaemia-specific immune response is a crucial step in tumour immunology that can mislead to tumour tolerance either by T cell ignorance, deletion or Treg induction. To resemble the situation of acute lymphoblastic leukaemia (ALL) in patients, we used the murine BALB/c model with syngeneic BM185 tumour cells. We established a tumour cell line that expresses the neo-antigen ovalbumin (BM185-OVA/GFP) to allow the application of T cell receptor transgenic, antigen-specific CD4(+) T cells. Here, we demonstrate that effective anti-ALL immunity can be established by in vivo priming of CD4(+) T cells that is sufficient to differentiate into effector cells. Yet they failed to control tumour alone, but initiated a Th1 response. An efficient tumour clearance was dependent on both antigen-specific CD4(+) T cells and CD8(+) effector T cells from the endogenous repertoire. The tolerogeneic milieu was characterized by increased Tregs numbers and elevated IL-10 level. Tregs hamper effective antitumour immune response, but their depletion did not result in reduced tumour growth. In contrast, neutralization of IL-10 improved median mouse survival. Future therapies should focus on establishing a strong CD4+ T cells response, either by adjuvant or by adoptive transfer.

Pathogenetic role of glomerular CXCL13 expression in lupus nephritis.

Podocytes maintain the structure and function of the glomerular filtration barrier. However, podocytes have recently been implicated in the innate immune response, and their function as non-haematopoietic antigen-presenting cells was highlighted. We have shown previously that excessive expression of the chemokine CXCL13 is a distinctive early event for nephritis in a murine model of systemic lupus erythematosus (SLE). Furthermore, we found that CXCL13 is elevated significantly in the serum of patients with SLE-nephritis. In this study, we were able to show for the first time that (i) CXCL13 is expressed locally in glomeruli in a model for SLE-nephritis in mice and that (ii) incubation of human podocytes with CXCL13 induces receptor stimulation of CXCR5 with activation of signalling pathways, resulting in (iii) secretion of proinflammatory cytokines and chemokines in culture supernatant. This cytokine/chemokine cocktail can lead to (iv) a neutrophil respiratory burst in isolated human granulocytes. Taken together, our results provide further evidence that CXCL13 is involved in the pathogenesis of glomerulonephritis and that podocytes can play an active role in local proinflammatory immune responses. Thus, CXCL13 could be a direct target for the therapy of glomerulonephritis in general and for SLE-nephritis in particular.

Different natural killer (NK) receptor expression and immunoglobulin E (IgE) regulation by NK1 and NK2 cells.

Many studies concerning the role of T cells and cytokines in allergy have been performed, but little is known about the role of natural killer (NK) cells. Accordingly, the expression of co-stimulatory, inhibitory and apoptosis receptors, cytokine profiles and their effect on immunoglobulin isotypes were investigated in polyallergic atopic dermatitis (AD) patients with hyper immunoglobulin E (IgE) and healthy individuals. AD patients showed significantly decreased peripheral blood NK cells compared to healthy individuals. Freshly isolated NK cells of polyallergic patients spontaneously released higher amounts of interleukin (IL)-4, IL-5, IL-13 and interferon (IFN)-gamma compared to healthy individuals. NK cells were differentiated to NK1 cells by IL-12 and neutralizing anti-IL-4 monoclonal antibodies (mAb), and to NK2 cells by IL-4 and neutralizing anti-IL-12 mAb. Following IL-12 stimulation, NK cells produced increased levels of IFN-gamma and decreased IL-4. In contrast, stimulation of NK cells with IL-4 inhibited IFN-gamma, but increased IL-13, production. The effect of NK cell subsets on IgE regulation was examined in co-cultures of in vitro differentiated NK cells with peripheral blood mononuclear cells (PBMC) or B cells. NK1 cells significantly inhibited IL-4- and soluble CD40-ligand-stimulated IgE production; however, NK2 cells did not have any effect. The inhibitory effect of NK1 cells on IgE production was blocked by neutralization of IFN-gamma. Except for CD40, NK cell subsets showed different expression of killer-inhibitory receptors and co-stimulatory molecules between the polyallergic and healthy subjects. These results indicate that human NK cells show differences in numbers, surface receptor and cytokine phenotypes and functional properties in AD.

Calcium signaling through the beta 2-cytoplasmic domain of LFA-1 requires intracellular elements of the T cell receptor complex.

The beta(2) integrin LFA-1 is an important cell-cell adhesion receptor of the immune system. Evidence suggests that the molecule also participates in signaling and co-stimulatory function. We show here that clustering of the intracellular domain of the beta(2) chain but not of the alpha(L)- or beta(1)-cytoplasmic domains, respectively, triggers intracellular Ca(2+) mobilization in Jurkat cells. A beta(2)-specific NPXF motif, located in the C-terminal portion of the beta(2) tail, is required for Ca(2+) signaling, and we show that this motif is important for the induction of allo-specific target cell lysis by cytotoxic T cells in vitro. Significantly, the Ca(2+)-signaling capacity of the beta(2) integrin is abrogated in T cells that do not express the T cell receptor but may be reconstituted by co-expression of the T cell receptor-zeta chain. Our data suggest a specific function of the cytoplasmic domain of the beta(2) integrin chain in T cell signaling.

Gene transfer of human interferon gamma complementary DNA into a renal cell carcinoma line enhances MHC-restricted cytotoxic T lymphocyte recognition but suppresses non-MHC-restricted effector cell activity.

Even though renal cell carcinomas (RCC) are thought to be immunogenic, many tumors express variations in surface molecules and intracellular proteins that hinder induction of optimal antitumor responses. Interferon gamma (IFNgamma) stimulation can correct some of these deficiencies. Therefore, we introduced the complementary DNA (cDNA) encoding human IFNgamma into a well-characterized RCC line that has been selected for development of an allogeneic tumor cell vaccine for treatment of patients with metastatic disease. Studies were performed to determine how endogenous IFNgamma expression influences tumor cell immunogenicity. IFNgamma transductants showed minimal increases in surface expression of MHC class I and adhesion molecules but expression of class II molecules was induced. Proteins of the transporter associated with antigen processing (TAP) and low molecular weight polypeptide (LMP) were constitutively expressed at high levels. The transductants stimulated allospecific cytotoxic T lymphocytes (CTL); however, they were not better than unmodified tumor cells in this capacity. Endogenous IFNgamma expression enhanced tumor cell recognition by MHC-restricted, tumor antigen-specific CTL but suppressed recognition by non-MHC-restricted cytotoxic cells. Thus, the functional consequences of IFNgamma expression varied with respect to the type of effector cell and were not always beneficial for tumor cell recognition.

Non-MHC-restricted CD4+ T lymphocytes are regulated by HLA-Cw7-mediated inhibition.

Natural killer cells (NK cells) represent an important component of innate immunity with the capacity to kill many tumor and virus-infected cells. The discovery of several classes of killer cell inhibitory receptors expressed by NK cells that bind specific MHC class I ligands on target cells provides detailed insight into the regulation of NK cells. Inhibitory receptors deliver negative signals following MHC ligand binding that abrogate cytotoxicity and, thus, determine the specificity of NK effector cell function. Here, we describe a novel subset of human memory CD4(+) T lymphocytes that display an NK-like pattern of regulation. These CD4(+) T cells display non-MHC-restricted cytotoxicity that is governed by HLA-Cw7 mediated inhibition. In NK cells, such specificity is associated with expression of the inhibitory receptor p58.2. In contrast, neither p58.2 nor other known inhibitory receptors were detected on these non-MHC-restricted CD4(+) T cells. This suggests that these cells are regulated by a hitherto unknown inhibitory receptor. The finding that interactions with MHC molecules downregulate the function of these CD4(+) T cells suggests that these non-MHC-restricted T cells may function to detect and eliminate cells with aberrant MHC expression.

Cellular and molecular analyses of major histocompatibility complex (MHC) restricted and non-MHC-restricted effector cells recognizing renal cell carcinomas: problems and perspectives for immunotherapy.

Renal cell carcinomas belong to the small group of tumors that are able to induce antitumor responses. Here we describe two general types of cytotoxic effector lymphocytes that can eliminate autologous tumor cells and discuss the role that major histocompatibility complex encoded molecules play in governing their specificities. Improved understanding of the cellular and molecular basis of renal cell carcinoma recognition opens new avenues of research with the potential to develop better immunotherapies for patients with metastatic disease.

HLA-C revisited. Ten years of change.

During the past 10 years knowledge about the interactions between major histocompatibility complex (MHC) class I molecules and the T-cell receptor (TCR) complex of cytotoxic T-cells (CTL) has developed dramatically. But the primary interest, both with respect to structure as well as function, has concentrated on HLA-A and -B molecules because of their high sequence polymorphism and their dominating presence at the cell surface. In contrast, HLA-C molecules seemed to be of only minor importance in the cascade of immune reactions owing to their more limited polymorphism and reduced levels of surface expression. The inability to define a number of antigen specificities had the result that HLA-C molecules were often neglected in studies of immune response, transplantation, and disease association. More recently a new function has been identified for HLA class I molecules where they act as inhibitors of the lytic capacity of natural killer (NK) cells and non-MHC-restricted T-cells. Moreover, the understanding of this novel mode of negative regulation of cytotoxicity was remarkably influenced by HLA-C since these were the first HLA class I molecules found to have such inhibitory potential. With this new inhibitory function serving as an essential component of the immune system, HLA-C molecules can no longer be neglected.

Expression of HLA-C molecules confers target cell resistance to some non-major histocompatibility complex-restricted T cells in a manner analogous to allospecific natural killer cells.

Specific HLA molecules have recently been shown to confer target cell resistance to lysis by some CD3- natural killer (NK) cells. For certain NK clones, resistance is governed by two specificities (NK1 and NK2) that are associated with particular HLA-C alleles: in general, target cells expressing Cw1, Cw3, Cw7, or Cw8 are susceptible to NK1 but resistant to NK2 clones, whereas target cells expressing Cw2, Cw4, Cw5, or Cw6 are susceptible to NK2 and resistant to NK1 cells. These two clusters of HLA-C alleles are distinguished by a dimorphism in the alpha 1 helical region, localized at amino acid positions 77 and 80. In this report, we show that highly enriched CD3+/CD56- cytotoxic T cell sublines and CD3-/CD56+ NK sublines derived from the same donor have identical cytolytic specificities when tested against a panel of allogeneic LCL and various HLA-B and -C transfectant cell lines. The lysis pattern of the allogeneic cells appeared to be related to the NK2 specificity for both effector cells: LCL expressing HLA-Cw2, Cw4, Cw5, or Cw6 alleles were lysed, while LCL expressing HLA-Cw1, Cw3, or Cw7 molecules were resistant. Resistance to lysis could be conferred to susceptible target cells by transfection with a Cw*0702 gene, while expression of a Cw*0602 gene did not provide protection. Similar patterns of HLA-C-mediated resistance were also found with two polyclonal T cell lines generated from the peripheral blood lymphocytes of unrelated donors. Thus, major histocompatibility complex (MHC) molecules that induced resistance to particular NK cells also regulated target cell resistance to lysis by these non-MHC-restricted effector T cells. For both types of effector cells, direct binding to HLA-C molecules was necessary to achieve inhibition since preincubation with mAb specific for class I molecules destroyed the protection from lysis of HLA-Cw7 expressing target cells. mAbs specific for CD3 and CD8 molecules had no influence on lysis or inhibition of the NK-like T cells. Formation of MHC complexes with particular peptides did not appear to be essential to confer resistance, since a cell line with defective peptide transporter genes (TAP genes), when transfected with an appropriate HLA-C allele, was as resistant to lysis as HLA-C transfectant lines with normal TAP function. These results suggest that HLA-C molecules may deliver negative regulatory signals to some non-MHC-restricted T cells in a manner similar to that described previously for particular NK cells.