Testing recombinant adeno-associated virus-gene loading of dendritic cells for generating potent cytotoxic T lymphocytes against a prototype self-antigen, multiple myeloma HM1.24

Abstract

Recent studies demonstrate that recombinant adeno-associated virus (rAAV)-based antigen loading of dendritic cells (DCs) generates significant and rapid (one stimulation per week) cytotoxic T-lymphocyte (CTL) responses in vitro against viral antigens. As a more extensive analysis of the rAAV system, we have used a selfantigen, HM1.24, expressed in multiple myeloma (MM). Again, with one stimulation, significant major histocompatibility complex (MHC) class 1-restricted, anti-HM1.24-specific CTL killing was demonstrated against MM cells. Furthermore, higher expression of interferon-␥ (IFN-␥) in T cells and higher expression levels of, in order of significance, CD80 (2.6-to 3.8-fold increase), CD86, and CD40 on DCs were also observed. The use of synthetic HM1.24-positive target cells further demonstrated the antigen specificity of these CTLs. There was also no evidence of natural killer cell involvement. These data extend our earlier studies and suggest that the rAAV-loading of DCs may be a particularly good protocol for generating CTLs against self-antigens, which may not otherwise be considered good targets because of their low immunogenicity. We also show that HM1.24 may be an effective antigen for targeting MM. IntroductionMultiple myeloma (MM) is a malignancy characterized by clonal proliferation and accumulation of immunoglobulin-producing plasma cells, which are terminally differentiated B cells. 1 It is important to note that patients who have not responded to high-dose chemotherapy treatment plus autologous stem cell transplantation respond well to allogeneic transplantation and that a graft-versus-myeloma effect can be extremely powerful. 2 These studies suggest that immunologic manipulations might be an appropriate treatment avenue for myeloma, especially if a state of minimal residual disease can be achieved after autotransplantation. In the search for an appropriate anti-MM antigenic target for immunotherapy, the self-antigen HM1.24 protein appears plausible. The HM1.24 antigen is defined by a monoclonal antibody (mAb HM1.24) that appears to be a novel terminal B-cellrestricted antigen 3,4 expressed on tumor cells and on mature immunoglobulin-secreting B cells (plasma cells and lymphoplasmacytoid cells) but not on other cells in the peripheral blood, bone marrow, liver, spleen, kidney, or heart of healthy persons or patients with non-plasma-cell-related malignancies. HM1.24 effectiveness against MM has been demonstrated through tumor cell lysis by mAb and complement. 5,6 The HM1.24 coding sequence is 1 kb long, an ideal size for ligation into any viral vector including adeno-associated virus (AAV). 4 Manipulating antigen-presenting cells, such as dendritic cells (DCs), is a recognized approach toward developing effective immunotherapeutic protocols. DCs are potent, professional antigenpresenting cells that can initiate a primary immune response to antigens by naive T cells. 7 Various protocols for generating DCs in vitro from peripheral blood have recently been developed. These new technologies permit ...

The antigenic landscape of multiple myeloma: mass spectrometry (re)defines targets for T-cell–based immunotherapy

“…24 An array of myeloma-associated T-cell antigens has been described in previous studies. [25][26][27][28][29][30][31][32][33][34][35] Most of these antigens were identified based on gene expression analysis and reverse immunology. Some of these antigens (WT1, 36,37 RHAMM, 38,39 hTERT, 40 and Survivin 40,41 ) have already found their way into clinical trials, showing promising results in terms of induction of specific T-cell responses as well as clinical responses in single patients.…”

Ex vivo generation of genetically modified dendritic cells for immunotherapy: implications of lymphocyte contamination

“…Rapid induction of CTL response from naïve T-cell precursors after stimulation with neo-or self-antigen-loaded DC is not a new finding and has been demonstrated previously in several studies. [53][54][55] We believe it likely that there are multiple reasons for the rapid induction of CTL response Immune responses to gene-modified dendritic cells N Chinnasamy et al against eGFP + DCs in our DC culture system. One reason is the high transduction frequency of DCs and transgene expression we have observed (B90%) with Lenti-eGFP vector.…”

Immune responses to gene therapy vectors: influence on vector function and effector mechanisms

“…has been used to generate cytotoxic responses to tumor or virus antigens in antitumor vaccination strategies, 4,22 or anti-HIV vaccination. 23 A T-cell response specific of the transgene and responsible for elimination of the infected cells can occur, however, in some situations.…”