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Lymphodepletion and infusion of autologous expanded tumour-infiltrating lymphocytes is effective therapy for patients with malignant melanoma. Antitumour responses are likely to be mediated by HLA class I- and II-restricted immune responses directed at tumour antigens. We assessed whether the peripheral blood of normal HLA-matched siblings of patients with melanoma could be used to generate lymphocytes with antimelanoma activity for adoptive immunotherapy after allogeneic blood or marrow transplantation. Melanoma cell lines were derived from two donors and were used to stimulate the mononuclear cells of three HLA-identical siblings. CD4(+) clones dominated cultures. Of these, approximately half were directly cytotoxic towards recipient melanoma cells and secreted interferon-gamma in response to tumour stimulation. More than half of the noncytotoxic clones also secreted interferon-gamma after melanoma stimulation. No CD4(+) clones responded to stimulation with recipient haemopoietic cells. The majority of CD8(+) clones directly lysed recipient melanoma, but did not persist in long-term culture in vitro. No crossreactivity with recipient haemopoietic cells was observed. The antigenic target of one CD4(+) clone was determined to be an HLA-DR11-restricted MAGE-3 epitope. Antigenic targets of the remaining clones were not elucidated, but appeared to be restricted through a non-HLA-DR class II molecule. We conclude that the blood of allogeneic HLA-matched sibling donors contains melanoma-reactive lymphocyte precursors directed at tumour-associated antigens. Adoptive immunotherapy with unselected or ex vivo-stimulated donor lymphocytes after allogeneic stem cell transplantation has a rational basis for the treatment of malignant melanoma.

Dendritic cells have been used effectively to select for human cytomegalovirus (CMV)-specific T cells for immunotherapy applications. The ability to process and present relevant major histocompatibility complex class I and II peptides to T cells makes them ideal for selecting CD4+ and CD8+ T cells regardless of HLA tissue type. This study compared the generation of CMV-specific T cells by using dendritic cells loaded with either CMV pp65(495–503) peptide or CMV lysate or transduced with adenovirus encoding the pp65 gene (Ad5pp65GFP) for the generation of CD4+ and CD8+ CMV-specific T cells in HLA-A2+ and HLA-A2− donors. In HLA-A2+ donors, CD8+ tetramer+ T cells increased with all antigens but were greatest in peptide- and Ad5pp65GFP-stimulated T cells. The CD4+/CD8+ ratio in the stimulated T-cell cultures proved to be dependent on the antigen used. CMV lysate-stimulated cells were primarily CD4+, whereas peptide- and Ad5pp65GFP-stimulated cultures were mostly CD8+. Analysis of cells from lysate-stimulated or gene-transduced-stimulated cultures showed expansion of CMV-specific CD4+ T cells, indicating that major histocompatibility complex class II peptides were present in both antigens. Furthermore, CMV-specific T cells were generated from HLA-A2− donors by using Ad5pp65GFP transduction or CMV lysate stimulation and were able to recognize a pp65 peptide restricted to the HLA-B35 allele. These data indicate that either CMV lysate or adenovirus encoding CMV antigenic genes may be useful for the generation of both CD4+ and CD8+ CMV-specific T cells in donors irrespective of HLA tissue type and may be applicable to clinical immunotherapy.

Adoptive transfer of donor-derived cytomegalovirus (CMV)-specific cytotoxic T cell (CTL) clones can restore immunity in allogeneic stem cell transplant recipients, providing protection against CMV disease. Current methods for selecting and expanding CMV-specific T cell clones are technically difficult, making adoptive T cell therapy impractical for routine clinical use. In this study, we describe a method for ex vivo generation and expansion of high-purity CMV-specific CTL using peptide-pulsed dendritic cells as antigen-presenting cells. Generation of CMV-specific CTL in numbers sufficient for clinical use in the time span of 4 weeks was accomplished in 6 of 8 CMV-seropositive donors. Examination of pp65 specificity by HLA/peptide tetramer staining demonstrated that a purity of greater than 95% peptide-specific cells could be obtained after two weekly stimulations and retained after further expansion for 3-4 weeks. Median expansion of total cell number was greater than 500-fold and expansion of peptide-specific CTL by tetramer staining was greater than 1.7 x 10(5)-fold. Four weeks after initiating CTL culture, we were able to generate greater than 10(9) total cells that specifically lysed target cells loaded with CMV peptide and cells infected with CMV. This simple and rapid method for generating high-purity CMV-specific CTL for adoptive immunotherapy is currently being examined for routine clinical use for allogeneic stem cell transplantation.

Excessive oxidative stress has been implicated in the induction of cell death in a variety of neurodegenerative diseases. In the present study, hydrogen peroxide (H2O2)-induced cell death in rat C6 glioma cells was used as a model system for studying the molecular events associated with oxidative stress-induced cell death in glial cells. We demonstrate that exposure of C6 glioma cells to H2O2 results in apoptotic cell death in a concentration-dependent manner, and caused activation of a member of the caspase-3-like family of proteases resulting in cleavage of the DNA repair enzyme poly(ADP-ribose)polymerase, PARP. Furthermore, H2O2 induced a transient activation of the transcription factor, nuclear factor kappa B (NF(Kappa)B). Pre-treatment of cells with the antioxidant N-acetylcysteine, (NAC), prevented both the activation of NF(Kappa)B and the induction of apoptosis by H2O2, suggesting a possible role for this transcription factor in oxidant-induced apoptosis in glial cells. Exposure of the cells to H2O2 led to transient activation of both c-Jun N-terminal kinase (JNK) and p38 kinase but has no effect on extracellular regulated kinase (ERK) activity. Inhibition of p38 by SB203580 did not protect the cells against H2O2-induced apoptosis suggesting that activation of p38 is not essential for H2O2-mediated cell death in C6 glioma cells.

Selective depletion of alloreactive T cells from allogeneic stem cell grafts can reduce graft-versus-host disease (GVHD) while preserving beneficial effects of T cells including facilitation of engraftment, protection against opportunistic infection, and reduced relapse risk. Memory T cells (CD62L–) represent a population of T cells that have previously encountered pathogens and may contain fewer T cells capable of recognizing neoantigens including recipient allogeneic antigen (aAg). We investigated whether human naive (CD62L+) or memory (CD62L–) T cells had different capacities to respond to aAg by assessing their ability to proliferate in response to and lyse HLA-mismatched Epstein-Barr virus–transformed B cells. Freshly sorted and in vitro expanded CD62L– memory T cells were less responsive to aAg stimulation than were CD62L+ naive T cells but contained higher levels of cytomegalovirus (CMV)–specific T cells. Analysis of T cell receptor (TCR) repertoire showed restricted TCR diversity in the memory T-cell population possibly due to selection associated with chronic exposure to common pathogens. Memory T cells may represent a donor cell subpopulation suitable for enhancing immune reconstitution without increasing the risk of GVHD.