Behavior of bone marrow-derived cells following in vivo transplantation: differentiation into stromal cells with roles in organ maintenance.

After injection of green fluorescent protein-positive (GFP(+)) bone marrow (BM) cells into lethally irradiated wild-type mice, the organs of the recipient mice [BM transplantation (BMT) mice] were regenerated; however, irradiation of the cecum or spleen (only) blocked their regeneration with loss of injected BM cells. These results suggest that the donor cells first enter the BM and then migrate to the peripheral organs. The maintenance of epithelial structure and function is controlled by interactions between stromal cells and the epithelia; the organ is stable only if the stroma is functioning normally. In BMT mice, intestinal GFP(+) stromal cells were regenerated fairly rapidly although GFP(+) cells were observed only rarely in the intestinal epithelium even if it passes several weeks or months post BMT, indicating that BM-derived stromal cells play a pivotal role in epithelial renewal and are crucial for maintaining organ structure and function. BM-derived cells in the periphery possess a special key to return to the BM and then to migrate to various organs to become resident cells.

Mismatched human leukocyte antigen class II-restricted CD8⁺ cytotoxic T cells may mediate selective graft-versus-leukemia effects following allogeneic hematopoietic cell transplantation.

Partial human leukocyte antigen (HLA)-mismatched hematopoietic stem cell transplantation (HSCT) is often performed when an HLA-matched donor is not available. In these cases, CD8(+) or CD4(+) T cell responses are induced depending on the mismatched HLA class I or II allele(s). Herein, we report on an HLA-DRB1*08:03-restricted CD8(+) CTL clone, named CTL-1H8, isolated from a patient following an HLA-DR-mismatched HSCT from his brother. Lysis of a patient Epstein-Barr virus-transformed B cell line (B-LCL) by CTL-1H8 was inhibited after the addition of blocking antibodies against HLA-DR and CD8, whereas antibodies against pan-HLA class I or CD4 had no effect. The 1H8-CTL clone did not lyse the recipient dermal fibroblasts whose HLA-DRB1*08:03 expression was upregulated after 1 week cytokine treatment. Engraftment of HLA-DRB1*08:03-positive primary leukemic stem cells in non-obese diabetic/severe combined immunodeficient/γc-null (NOG) mice was completely inhibited by the in vitro preincubation of cells with CTL-1H8, suggesting that HLA-DRB1*08:03 is expressed on leukemic stem cells. Finally, analysis of the precursor frequency of CD8(+) CTL specific for recipient antigens in post-HSCT peripheral blood T cells revealed a significant fraction of the total donor CTL responses towards the individual mismatched HLA-DR antigen in two patients. These findings underscore unexpectedly significant CD8 T cell responses in the context of HLA class II.

HapMap scanning of novel human minor histocompatibility antigens.

Minor histocompatibility antigens (mHags) are molecular targets of allo-immunity associated with hematopoietic stem cell transplantation (HSCT) and involved in graft-versus-host disease, but they also have beneficial antitumor activity. mHags are typically defined by host SNPs that are not shared by the donor and are immunologically recognized by cytotoxic T cells isolated from post-HSCT patients. However, the number of molecularly identified mHags is still too small to allow prospective studies of their clinical importance in transplantation medicine, mostly due to the lack of an efficient method for isolation. Here we show that when combined with conventional immunologic assays, the large data set from the International HapMap Project can be directly used for genetic mapping of novel mHags. Based on the immunologically determined mHag status in HapMap panels, a target mHag locus can be uniquely mapped through whole genome association scanning taking advantage of the unprecedented resolution and power obtained with more than 3 000 000 markers. The feasibility of our approach could be supported by extensive simulations and further confirmed by actually isolating 2 novel mHags as well as 1 previously identified example. The HapMap data set represents an invaluable resource for investigating human variation, with obvious applications in genetic mapping of clinically relevant human traits.

Identification of a polymorphic gene, BCL2A1, encoding two novel hematopoietic lineage-specific minor histocompatibility antigens.

We report the identification of two novel minor histocompatibility antigens (mHAgs), encoded by two separate single nucleotide polymorphisms on a single gene, BCL2A1, and restricted by human histocompatibility leukocyte antigen (HLA)-A*2402 (the most common HLA-A allele in Japanese) and B*4403, respectively. Two cytotoxic T lymphocyte (CTL) clones specific for these mHAgs were first isolated from two distinct recipients after hematopoietic cell transplantation. Both clones lyse only normal and malignant cells within the hematopoietic lineage. To localize the gene encoding the mHAgs, two-point linkage analysis was performed on the CTL lytic patterns of restricting HLA-transfected B lymphoblastoid cell lines obtained from Centre d'Etude du Polymorphisme Humain. Both CTL clones showed a completely identical lytic pattern for 4 pedigrees and the gene was localized within a 3.6-cM interval of 15q24.3-25.1 region that encodes at least 46 genes. Of those, only BCL2A1 has been reported to be expressed in hematopoietic cells and possess three nonsynonymous nucleotide changes. Minigene transfection and epitope reconstitution assays with synthetic peptides identified both HLA-A*2402- and B*4403-restricted mHAg epitopes to be encoded by distinct polymorphisms within BCL2A1.

Epstein-Barr virus nuclear antigen 1-specific CD4+ T cells directly kill Epstein-Barr virus-carrying natural killer and T cells.

Epstein-Barr virus (EBV) nuclear antigen (EBNA)1 is expressed in every EBV-infected cell, regardless of the state of EBV infection. Although EBNA1 is thought to be a promising antigen for immunotherapy of all EBV-associated malignancies, it is less clear whether EBNA1-specific CD4(+) T cells can act as direct effectors. Herein, we investigated the ability of CD4(+) T-cell clones induced with overlapping peptides covering the C-terminal region of EBNA1, and identified minimal epitopes and their restricted major histocompatibility complex class II molecules. Of these, a novel epitope, EYHQEGGPD, was found to be presented by DRB1*0401, 0403 and 0406. Five CD4(+) T-cell clones recognized endogenously processed and presented antigens on EBV-transformed lymphoblastoid cell lines (LCL) and one example proved capable of killing EBV-carrying natural killer (NK) and T-cell lines derived from patients with chronic active EBV infection (CAEBV). Identification of minimal epitopes facilitates design of peptide-based vaccines and our data suggest that EBNA1-specific CD4(+) T cells may play roles as direct effectors for immunotherapy targeting EBV-carrying NK and T-cell malignancies.

Effective induction of anti-tumor immune responses with oligomannose-coated liposome targeting to intraperitoneal phagocytic cells.

We recently established a novel drug delivery system (DDS) using oligomannose-coated liposomes (OMLs) which are probably taken up by macrophages (Mvarphi) to carry anti-cancer drugs to milky spots known as preferential metastatic sites of gastric cancers [Y. Ikehara, T. Niwa, L. Biao, S.K. Ikehara, N. Ohashi, T. Kobayashi, Y. Shimizu, N. Kojima, H. Nakanishi, A carbohydrate recognition-based drug delivery and controlled release system using intraperitoneal macrophages as a cellular vehicle, Cancer Res. 66 (2006) 8740-8748]. In the present study, we applied this intraperitoneal DDS for systemic cancer immunotherapy employing ovalbumin (OVA) as a model antigen. The cells taking up the OMLs containing FITC-OVA injected into the peritoneal cavity were predominantly Mvarphi, as they showed adhesive characteristics and expressed F4/80 and CD11b almost exclusively. The phagocytic cells also took up bare OVA directly to the same extent as OML-enclosed OVA (OML-OVA), as it is a highly mannosilated protein. The phagocytic cells taking up OML-OVA, however, could activate OVA-specific CD8+ (from OT-I: H-2Kb/OVA257-264-specific) and CD4+ (from OT-II: H-2Ab/OVA323-339-specific) T cells much more effectively in vitro than those taking up bare OVA. Furthermore, only the mice pre-immunized with OML-OVA rejected E.G7-OVA (OVA-transfected EL4) but not EL4. These results indicate that the OMLs can also be used as an effective antigen delivery system for cancer immunotherapy activating both CTL and Th subsets.

Aberrant expression of BCL2A1-restricted minor histocompatibility antigens in melanoma cells: application for allogeneic transplantation.

It has been shown that allogeneic hematopoietic stem cell transplantation (HSCT) can be one of the therapeutic options for patients with metastatic solid tumors, such as renal cancer. However, the development of relatively severe GVHD seems to be necessary to achieve tumor regression in the current setting. Thus, it is crucial to identify minor histocompatibility antigens (mHags) only expressed in tumor cells but not GVHD target organs. In this study, we examined whether three mHags: ACC-1 and ACC-2 encoded by BCL2A1, and HA-1 encoded by HMHA1, could serve as such targets for melanoma. Real-time PCR and immunohistochemical analysis revealed that the expression of both BCL2A1and HMHA1 in melanoma cell lines and primary melanoma cells was comparable to that of hematopoietic cells. Indeed, melanoma cell lines were efficiently lysed by cytotoxic T lymphocytes specific for ACC-1, ACC-2, and HA-1. Our data suggest that targeting mHags encoded not only by HMHA1, whose aberrant expression in solid tumors has been reported, but also BCL2A1 may bring about beneficial selective graft-versus-tumor effects in a population of melanoma patients for whom these mHags are applicable.

Generation of peptide-specific CD8+ T cells by phytohemagglutinin-stimulated antigen-mRNA-transduced CD4+ T cells.

Functional analysis of antigen-specific CD8(+) T cells is important for understanding the immune response in various immunological disorders. To analyze CD8(+) T cell responses to a variety of antigens with no readily defined peptides available, we developed a system using CD4(+) phytohemagglutinin (PHA) blasts transduced with mRNA for antigen molecules. CD4(+) PHA blasts express MHC class I and II, and also CD80 and CD86 and are thus expected to serve as potent antigen presenting cells. EGFP mRNA could be transduced into and the protein expressed by more than 90% of either LCL or CD4(+) PHA blasts. Its expression stably persisted for more than 2 weeks after transduction. In experiments with HLA-A*2402 restricted CD8(+) CTL clones for either EBNA3A or a cancer-testis antigen, SAGE, mRNA-transduced lymphoid cells were appropriate target cells in ELISPOT assays or (51)Cr releasing assays. Finally, using CD4(+) PHA blasts transduced with mRNA of a cancer-testis antigen MAGE-A4, we successfully generated specific CTL clones that recognized a novel HLA-B*4002 restricted epitope, MAGE-A4(223-231). Messenger RNA-transduced CD4(+) PHA blasts are thus useful antigen presenting cells for analysis of CD8(+) T cell responses and induction of specific T cells for potential immunotherapy.

Characterization of murine CD160+ CD8+ T lymphocytes.

CD160 is an Ig-like glycoprotein expressed on NK, NKT and TCRgammadelta T cells, as well as intestinal intraepithelial T lymphocytes. In addition, a minor subset of CD8(+) but not CD4(+) T cells in the periphery is also known to express CD160, but the subset has not been fully characterized. In this study, we prepared anti-murine CD160 mAbs and investigated the expression profile of CD160 on various subsets of CD8(+) T cells. The amount of CD160 on almost all CD8(+) T cells was increased upon CD3-mediated stimulation in vitro, and soluble CD160 was found to be released. Flow cytometric analysis revealed most CD8(+) T cells expressing CD160 to show a CD44(high) phenotype in vivo. On further analysis, both CD44(high)CD62L(low) effector memory T cells (T(EM)) and CD44(high)CD62L(high) central memory T cells (T(CM)) expressed CD160 at an intermediate level. High levels were evident with recently activated CD8(+) T(EM). Naïve CD8(+) T cells presumably immediately after stimulation (CD44(low)CD62L(low)CD69(+)) also expressed CD160, but only at a low level. Purified CD160(+) CD8(+) T cells from OT-1 transgenic mice expressing TCR against OVA residues 257-264 presented by H-2K(b) produced IFN-gamma more rapidly than CD160(-) CD8(+) T cells upon antigen stimulation. These results together show that CD160 is expressed on the majority of CD8(+) memory T cells as well as recently activated CD8(+) T cells.

Adjuvant-mediated tumor regression and tumor-specific cytotoxic response are impaired in MyD88-deficient mice.

The Mycobacterium bovis bacillus Calmette-Guérin cell-wall skeleton (BCG-CWS) activates Toll-like receptor (TLR) 2 and TLR4, but unlike the typical TLR4 agonist bacterial lipopolysaccharide barely induces type 1 IFN. BCG-CWS has been used for adjuvant immunotherapy for patients with cancer. We investigated the adjuvant potential of BCG-CWS for induction of CTLs subsequent to TLR-mediated dendritic cell (DC) maturation, using a syngeneic mouse tumor model (B16 melanoma in C57BL/6). We evaluated the retardation of tumor growth and cytotoxic response in wild-type and MyD88-/- mice immunized with tumor debris and/or BCG-CWS. Delays in tumor growth and cytotoxic response were induced by immunization with a mixture of BCG-CWS emulsion and the tumor. BCG-CWS was capable of activating DCs ex vivo by the criteria of CD80/CD86 up-regulation and cytokine (interleukin-12, tumor necrosis factor-alpha) induction. Efficient tumor suppression and ex vivo cytokine induction did not occur in MyD88-deficient mice and cells, suggesting that the MyD88 adapter is crucial for induction of tumor cytotoxicity. Because TLR4 is involved in both MyD88-dependent and -independent pathways and the latter affects DC maturation, our findings indicate that both pathways cooperate to induce CTL-based tumor immunity.

Detailed characterization of a homozygously deleted region corresponding to a candidate tumor suppressor locus at distal 17p13.3 in human lung cancer.

17p13.3 is one of the chromosomal regions most frequently affected by allelic loss in a variety of human neoplasms including lung cancer. A number of loss of heterozygosity (LOH) analyses have suggested the existence of a tumor suppressor gene at 17p13.3, distal to the p53 locus at 17p13.1. In the present study, we characterized a homozygous deletion at 17p13.3 in a small cell lung cancer cell line by constructing a bacterial artificial chromosome (BAC) contig and a restriction map surrounding the region, as well as by utilizing publicly available draft sequences. We defined the breakpoint, assigned and analysed two known genes, 14-3-3 epsilon and CRK, and a novel gene LOST1 within or at the end of the homozygous deletion of about 170 kb in size. Marked reduction of LOST1 expression was detected in 69% (11/16) of lung cancer specimens by quantitative real-time RT-PCR, while significant DNA hypermethylation was observed at the 5' end of the LOST1 gene in four of six lung cancer cell lines with negligible LOST1 expression. We also show here that a polymorphic marker D17S1174, which resides within the homozygous deletion, was apparently located in the middle of the minimum LOH region, providing further supportive evidence for the presence of a tumor suppressor gene(s) in this region.

Gene expression-based, individualized outcome prediction for surgically treated lung cancer patients.

Individualized outcome prediction classifiers were successfully constructed through expression profiling of a total of 8644 genes in 50 non-small-cell lung cancer (NSCLC) cases, which had been consecutively operated on within a defined short period of time and followed up for more than 5 years. The resultant classifier of NSCLCs yielded 82% accuracy for forecasting survival or death 5 years after surgery of a given patient. In addition, since two major histologic classes may differ in terms of outcome-related expression signatures, histologic-type-specific outcome classifiers were also constructed. The resultant highly predictive classifiers, designed specifically for nonsquamous cell carcinomas, showed a prediction accuracy of more than 90% independent of disease stage. In addition to the presence of heterogeneities in adenocarcinomas, our unsupervised hierarchical clustering analysis revealed for the first time the existence of clinicopathologically relevant subclasses of squamous cell carcinomas with marked differences in their invasive growth and prognosis. This finding clearly suggests that NSCLCs comprise distinct subclasses with considerable heterogeneities even within one histologic type. Overall, these findings should advance not only our understanding of the biology of lung cancer but also our ability to individualize postoperative therapies based on the predicted outcome.

Production and characterization of an active single-chain variable fragment antibody recognizing CD25.

The alpha subunit of the interleukin-2 receptor (IL-2Ralpha, CD25) is a potential target in therapeutic approaches for hematolopoietic malignancies expressing CD25 on their cell surface, such as adult T cell leukemia/lymphomas. Recent reports have demonstrated that depletion of CD4+CD25+ regulatory T cells with anti-CD25 antibodies may enhance host tumor immunity. We previously raised a mouse monoclonal antibody (mAb), Ta60b mAb (IgG1kappa), specifically recognizing CD25, and an attempt was made here to produce a single chain Fv fragment (scFv) from this mAb as an initial step to development of scFv-based therapeutics. cDNA fragments encoding for the variable regions of the light and heavy chains of the Ta60b mAb were thus isolated by polymerase chain reaction-mediated cloning, and, an expression vector constructed to express Ta60b scFv fused with the maltose binding protein (MBP) in the periplasm of Escherichia coli. The soluble form of MBP-Ta60b fused scFv could be extracted and affinity-purified with an amylose/agarose column, allowing its immunoreactivity to be analyzed by enzyme-linked immunosorbent assay (ELISA), mixed hemadsorption assay, and fluorescence activated cell sorting. In addition, binding activity was studied by competitive ELISA and surface plasmon resonance. The results showed that Ta60b scFv obtained from periplasm retains good reactivity, although its KD value was 4-fold lower than that of the whole Ta60b antibody, suggesting possible clinical use for treatment of patients with CD25-expressing tumors and also for enhancing anti-tumor immunity.

CD56/NCAM-positive Langerhans cell sarcoma: a clinicopathologic study of 4 cases.

This report concerns the clinicopathologic features of 4 patients with CD56/neural cell adhesion molecule (NCAM)-positive Langerhans cell sarcoma (LCS). Three of the patients were elderly, between 59 and 62 years of age at presentation, and the other was 35 years old. The presenting symptoms included fever, bone pain, and weakness. The patients shared some clinical findings, such as multiorgan involvement of lymph nodes, skin, lung, bone marrow, and spleen. LCS carries a poor prognosis, and 3 of the patients died of the disease within several years of presentation despite multiagent chemotherapy and radiotherapy. Of special interest is that all of the cases showed CD56 expression on the tumor cells in addition to expression of CD1a, S100beta, and langerin, the presence of which suggests derivation from Langerhans cells. For control, CD56 was also examined in 8 cases of Langerhans cell histiocytosis (LCH), a single-system unifocal or multifocal disease, and the results of staining of the tumor cells were negative. Our findings indicated that CD56 may be a clinically relevant biologic marker for predicting an intractable course of Langerhans cell neoplasms, although it is often difficult to draw a definite morphologically-based distinction between LCS and LCH.

Significant growth inhibition of human lung cancer cells both in vitro and in vivo by the combined use of a selective cyclooxygenase 2 inhibitor, JTE-522, and conventional anticancer agents.

This study reports that a selective COX-2 inhibitor JTE-522inhibits both in vitro and in vivo growth of human lung cancer cells as a single agent. Furthermore, the adjunct use of JTE-522 is shown to significantly enhance treatment efficacy of conventional anticancer drugs not only in vitro but also in vivo without causing any noticeable side effects. Indeed, IC(50)s of various anticancer agents in vitro were reduced by up to 70%, whereas the combination therapy of JTE-522 with docetaxel and vinorelbine inhibited tumor growth in vivo by 65 and 55%, respectively. Taken together, these findings suggest that the use of a selective COX-2 inhibitor in the treatment of lung cancer may be promising, especially because of its enhancement of the treatment efficacy of conventional anticancer agents without compromising quality of life.

The CC chemokine receptor 4 as a novel specific molecular target for immunotherapy in adult T-Cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATLL) is a peripheral T-cell neoplasm with dismal prognosis, and no optimal therapy has been developed. We tested the defucosylated chimeric anti-CC chemokine receptor 4 (CCR4) monoclonal antibody, KM2760, to develop a novel immunotherapy for this refractory tumor. In the presence of peripheral blood mononuclear cells (PBMCs) from healthy adult donors, KM2760 induced CCR4-specific antibody-dependent cellular cytotoxicity (ADCC) against CCR4-positive ATLL cell lines and primary tumor cells obtained from ATLL patients. We next examined the KM2760-induced ADCC against primary ATLL cells in an autologous setting. Antibody-dependent cellular cytotoxicity mediated by autologous effector cells was generally lower than that mediated by allogeneic control effector cells. However, a robust ADCC activity was induced in some cases, which was comparable with that mediated by allogeneic effector cells. It suggests that the ATLL patients' PBMCs retain substantial ADCC-effector function, although the optimal conditions for maximal effect have not yet been determined. In addition, we also found a high expression of FoxP3 mRNA and protein, a hallmark of regulatory T cells, in ATLL cells, indicating the possibility that ATLL cells originated from regulatory T cells. KM2760 reduced FoxP3 mRNA expression in normal PBMCs along with CCR4 mRNA by lysis of CCR4+ T cells in vitro. Our data suggest not only that the CCR4 molecule could be a suitable target for the novel antibody-based therapy for patients with ATLL but also that KM2760 may induce effective tumor immunity by reducing the number of regulatory T cells.

Targeted cloning of cytotoxic T cells specific for minor histocompatibility antigens restricted by HLA class I molecules of interest.

BACKGROUND: T cells specific for minor histocompatibility antigens (mHAgs) play a major role in both graft-versus-host disease and the graft-versus-tumor effect after HLA-identical bone marrow transplantation (BMT). However, characterization of individual T-cell responses to mHAgs is difficult and has generally involved extensive screening of T-cell clones isolated from bulk T-cell cultures generated from BMT recipients. In this report, we describe a new approach that permits both direct visualization of CD8 T-cell responses to mHAgs and cloning of T cells reacting with mHAgs presented by individual HLA alleles of interest. METHODS AND RESULTS: Panels of Epstein-Barr virus-transformed B-cell lines (B-LCL) expressing retrovirally transduced HLA cDNA were used as stimulator cells in an enzyme-linked immunospot (ELISPOT) assay to identify CD8 T cells reacting with mHAgs in cultures generated from postBMT recipient peripheral blood. T cells specific for mHAgs presented by selected HLA alleles could then be captured and cloned using an interferon-gamma secretion assay and magnetic bead selection. A majority of T-cell clones thus isolated exhibited cytolytic activity against the same HLA-transfected B-cell lines used for the ELISPOT assay. CONCLUSION: The ELISPOT assay was useful for identification of the HLA alleles presenting mHAgs recognized by individual T-cell lines. This approach for isolating mHAgs-specific CD8 T-cell clones should assist in characterizing responses restricted by HLA alleles of interest, which are common in a certain ethnic group.

Expression of cancer/testis (CT) antigens in lung cancer.

Cancer/testis (CT) antigens are considered promising candidates for vaccine-based immunotherapy. The aim of this study was to investigate which CT antigens should be targeted in immunotherapy of Japanese lung cancer. To determine the expression of 12 CT antigens in Japanese primary lung cancers and cell lines, a reverse-transcription polymerase chain reaction (RT-PCR) analysis was performed. Among 46 primary lung cancers, high expression rates were found for MAGE-3 (41%, 19/46), and SSX-4 (35%, 16/46). A similar pattern of CT antigen expression was observed in 29 lung cancer cell lines. The expression frequency of a certain CT antigen, namely NY-ESO-1, in Japanese cases was drastically different from that in Caucasians. Polyvalent CT antigen vaccine may be effective to increase the number of lung cancer patients eligible for cancer-specific immunotherapy. Vaccination with MAGE-3 and SSX-1 would cover 57% of all patients, with three antigens, MAGE-3, SSX-1, and MAGE-4, would cover 65%, and with four antigens, MAGE-3, SSX-1, MAGE-4 and SSX-4, would cover 70%. Simultaneous expression of two or more CT antigens was observed in 25/46 (54%) primary lung cancers and 18/29 (62%) lung cancer cell lines. Polyvalent CT antigen vaccines may be also effective to reduce a chance of emergence of antigen loss variants, thus preventing tumors from escaping from the immune system. For this purpose, vaccination with combinations of MAGE-3 with MAGE-6, SSX-4, MAGE-1 or BAGE may be effective for a quarter of Japanese lung cancer patients. In addition, in silico surveys of dbEST database were used for identification of new CT antigens. We identified a novel gene, TES101RP, expressed only in some small cell lung cancers (SCLC) and in testis, as confirmed by RT-PCR analysis.