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. ( Cancer Sci 2008; 99: 1633–1642)     

Human glioma associated and related antigens,identified by monoclonal antibodies

Summary Tumour specific and various tumour-associated antigens expressed on human glioma cells were reported from many laboratories. These have been identified by xeno-, allo-, or auto-sera and more recently by utilizing monoclonal antibodies produced by hybridoma technique.In this article, the results of reports are summarized comparing the studies with conventional antisera and monoclonal antibodies. The present and future clinical applications of these monoclonal antibodies are described.     

A functional RNAi screen for Runx2-regulated genes associated with ectopic bone formation in human spinal ligaments

Ossification of the posterior longitudinal ligament of the spine (OPLL) is characterized by ectopic ossification in the spinal ligaments, which enlarges with time and compresses the spinal cord, resulting in serious neurological symptoms. We previously reported that Runx2 expression was enhanced in spinal ligament cells from OPLL patients (OPLL cells). To clarify genes regulated by Runx2, Runx2 expression was first enhanced by culturing primary OPLL cells in osteogenic medium (OS induction) and then inhibited by siRNAs targeted to Runx2. DNA microarray demonstrated that in addition to chondrogenic factors such as connective tissue growth factor and cartilage oligomeric matrix protein, angiopoietin-1 was also significantly increased by OS induction and decreased by siRNAs for Runx2 in OPLL cells, suggesting that these genes are regulated by Runx2. However, these changes were not observed in non-OPLL control cells (from cervical spondylotic myelopathy patients). Furthermore, Runx2 was not decreased by siRNAs for angiopoietin-1. OS induction and RNAi inhibition of angiopoietin-1 expression was also observed in osteoblasts. Both siRNAs for Runx2 and angiopoietin-1 completely inhibited aggrecan-1 expression. These results suggest that angiopoietin-1 is downstream of Runx2 in both OPLL primary cells and osteoblasts. Angiopoietin-1 may play an important role in ectopic ossification.     

NF-κB RelA-deficient Lymphocytes: Normal Development of T Cells and B Cells, Impaired Production of IgA and IgG1 and Reduced Proliferative Responses

To investigate the function of NF-κB RelA (p65), we generated mice deficient in this NF-κB family member by homologous recombination. Mice lacking RelA showed liver degeneration and died around embryonic day 14.5. To elucidate the role of RelA in lymphocyte development and function, we transplanted fetal liver cells of 13.5-day embryos from heterozygote matings into irradiated SCID mice. Within 4 weeks, both T and B cells had developed in the SCID mice receiving relA−/− fetal liver transplants, similar to the relA+/+ and +/− cases. T cells were found to mature to Thy-1⁺/TCRαβ⁺/CD3⁺/CD4⁺ or CD8⁺, while B cells had the ability to differentiate to IgM⁺/B220⁺ and to secrete immunoglobulins. However, the secretion of IgG1 and IgA was reduced in RelA-deficient B cells. Furthermore, both T and B cells lacking RelA showed marked reduction in proliferative responses to stimulation with Con A, anti-CD3, anti-CD3+anti-CD28, LPS, anti-IgM, and PMA+calcium ionophore. The results indicate that RelA plays a critical role in production of specific Ig isotypes and also in signal transduction pathways for lymphocyte proliferation.     

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.     

Influenza A whole virion vaccine induces a rapid reduction of peripheral blood leukocytes via interferon-α-dependent apoptosis

Infection with single strand RNA (ssRNA) viruses, such as influenza A virus, is known to induce protective acquired immune responses, including the production of neutralizing antibodies. Vaccination also causes a reduction in the number of peripheral blood leukocytes (PBL) shortly after inoculation, a result which may have undesirable adverse effects. The cellular mechanisms for this response have not been elucidated so far. Here we report that formalin-inactivated influenza A whole virus vaccine (whole virion) induces a significant decrease in PBL in mice 5–16 h after administration, whereas an ether-split vaccine (HA split) made from the same influenza virus strain does not induce a similar loss of PBL. Concordant with this reduction in the number of PBL, a rapidly induced and massive production of interferon (IFN)-α is observed when mice are injected with whole virion, but not with HA split vaccines. The role of Toll-like receptors (TLR), which are involved in signal transduction of influenza virus, and the subsequent induction of IFNα were confirmed using mice lacking TLR7, MyD-88, or IFNα/β receptor. We further demonstrated that the observed PBL loss is caused by apoptosis in an IFNα-dependent manner, and not by leukocyte redistribution due to chemokine signaling failure. These findings indicate that RNA-encapsulated whole virion vaccines can rapidly induce a loss of leukocytes from peripheral blood by apoptosis, which may modulate the subsequent immune response.     

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.     

Systemic arterial supply to the normal basal segments of the left lower lobe treated by coil embolization, with long-term follow-up

We report a case of a 41-year-old woman who underwent therapeutic embolization of an aberrant systemic artery of the lung. Except for chest pains immediately after embolization, she recovered well and has not experienced hemoptysis in the past 6 years. In such patients, coil embolization could be an alternative choice of treatment, with the expectation of an excellent long-term result despite ischemia of the corresponding lung parenchyma.