Primary Allogeneic T-Cell Responses against Mantle Cell Lymphoma Antigen-Presenting Cells for Adoptive Immunotherapy after Stem Cell Transplantation

Allo-HLA reactivity of virus-specific memory T cells is common

Graft-versus-host disease and graft rejection are major complications of allogeneic HLA-mismatched stem cell transplantation or organ transplantation that are caused by alloreactive T cells. Because a range of acute viral infections have been linked to initiating these complications, we hypothesized that the cross-reactive potential of virus-specific memory T cells to allogeneic (allo) HLA molecules may be able to mediate these complications. To analyze the allo-HLA reactivity, T cells specific for Epstein-Barr virus, cytomegalovirus, varicella zoster virus, and influenza virus were tested against a panel of HLA-typed target cells, and target cells transduced with single HLA molecules. Eighty percent of T-cell lines and 45% of virus-specific T-cell clones were shown to cross-react against allo-HLA molecules. The cross-reactivity of the CD8 and CD4 T-cell clones was directed primarily against HLA class I and II, respectively. However, a restricted number of CD8 T cells exhibited cross-reactivity to HLA class II. T-cell receptor (TCR) gene transfer confirmed that allo-HLA reactivity and virus specificity were mediated via the same TCR. These results demonstrate that a substantial proportion of virus-specific T cells exert allo-HLA reactivity, which may have important clinical implications in transplantation settings as well as adoptive transfer of third-party virus-specific T cells.

Immunotherapy in mantle cell lymphoma: anti-CD20-based therapy and beyond

Mantle cell lymphoma (MCL), an aggressive non-Hodgkin's lymphoma characterized by t(11; 14)(q13; q32) chromosomal translocation and overexpression of cyclin D1, has the worst prognosis among all lymphomas. Recent advances in biology, genetics, and immunology have supported the development of immunotherapy in MCL. Rituximab monotherapy in MCL has limited activity. It is more effective when used in combination with chemotherapy such as R-CHOP, R-hyperCVAD/MTX-Ara-C, or R-FCM as front-line or salvage therapy for mantle cell lymphoma. Maintenance with Rituximab was shown to prolong response duration. Although most results have suggested that combining autologous stem cell transplantation with Rituximab may lead to durable remission, the sample size was not sufficient to declare survival benefit. Anti-CD20 radioimmunoconjugates (RICs) (90)Yttrium-ibritumomab tiuxetan and (131)Iodine-tositumomab have been used in mantle cell lymphoma even when patients are relatively resistant to Rituximab-based therapy. Allogeneic stem cell transplantation is a treatment modality in advanced or relapsed MCL, particularly using reduced-intensity conditioning. MCL may have high response rates and sustained remissions after donor lymphocyte infusion. Dendritic cells (DCs) fused with MCL cells for immunostimulation have preliminarily shown anti-lymphoma effects as well. Idiotype vaccination in MCL patients following Rituximab-containing chemotherapy induced tumor-specific T-cell immunity in the absence of B cells. Other immunotherapy, such as the combination of thalidomide with Rituximab, has shown substantial antitumor activity. A Phase I/II study is ongoing to determine the maximum tolerated dose (MTD) and the efficacy of lenalidomide in combination with Rituximab for relapsed/refractory MCL. This review summarizes the latest and exciting advances in MCL.

Graft-versus-host and graft-versus-leukemia reactions: a summary of the Seventh International Symposium held in Garmisch-Partenkirchen, Germany, February 22nd–25th, 2006, Tolerance and Immunity, an update on lymphoid malignancies

The Seventh International Symposium on graft-versus-host and graft-versus-leukemia reactions was held in Garmisch Partenkirchen (Germany, near Lake Riessersee) between January 22nd and 25th, 2006. A total of more than 100 invited participants (scientists and clinicians working in the area of allogeneic stem cell transplantation) discussed research in the area of lymphoid malignancies. Major topics of the 2006 meeting were lymphocyte biology, experimental systems, lymphoma pathogenesis, cellular therapy in vivo and vitro, idiotype-specific responses and graft-versus-malignancy reactions for lymphomas and multiple myeloma. Further highlights were immune responses to blasts of ALL, haploidentical transplantation, role of natural killer cells, clinical guidelines for allogeneic transplantation and adoptive immunotherapy in chronic lymphocytic leukemia and multiple myeloma, new antibody-mediated strategies. As can be seen in the summaries of the individual presentations, progress was made in the understanding of lymphoma biology and in the clinical application of graft-versus-lymphoma or graft-versus-myeloma effects. Each day was followed by round-table discussions, which summarized new data and challenged established concepts. The discussions resulted in new insights and projects for basic research and clinical transplantation.