Rapid generation of broad T-cell immunity in humans after a single injection of mature dendritic cells.
(17/1082)
Dendritic cells (DCs) are potent antigen-presenting cells that initiate protective T-cell immunity in mice. To study the immunogenicity of DCs in humans, we injected 9 healthy subjects subcutaneously with a control injection of autologous monocyte-derived, mature DCs, followed 4-6 weeks later by DCs pulsed with keyhole limpet hemocyanin (KLH), HLA-A*0201-positive restricted influenza matrix peptide (MP), and tetanus toxoid (TT). Four more subjects received these antigens without DCs. Injection of unpulsed DCs, or antigens alone, failed to immunize. Priming of CD4(+) T cells to KLH was observed in all 9 subjects injected with KLH-pulsed DCs, and boosting of TT-specific T-cell immunity was seen in 5 of 6 subjects injected with TT-pulsed DCs. Injection of antigen-pulsed DCs led to a severalfold increase in freshly isolated MP-specific, IFN-gamma-secreting CD8(+) T cells in all 6 HLA-A*0201-positive subjects, as early as 7 days after injection. When T cells were boosted in culture, there was an increase in MHC tetramer-binding cells and cytotoxic T cells after DC vaccination. These data provide the first controlled evidence of the immunogenicity of DCs in humans, and demonstrate that a single injection of mature DCs rapidly expands T-cell immunity. (+info)
Nested polymerase chain reaction with sequence-specific primers typing for HLA-A, -B, and -C alleles: detection of microchimerism in DR-matched individuals.
(18/1082)
It is widely accepted that donor leukocytes survive within the recipient periphery after blood transfusion or solid organ transplantation. The significance of this microchimerism remains unclear, partially because of the insecurity of assays used to detect the donor-derived material. The techniques used to detect donor-derived DNA within recipient peripheral blood rely largely on major histocompatibility complex class II polymorphism. We and others have shown that the sensitivity of polymerase chain reaction with sequence-specific primers (PCR-SSP) typing for HLA class II alleles can be increased 100-fold by the addition of a primary amplification step (nested PCR-SSP). We have now extended this technique to encompass typing for HLA class I alleles, thereby adding flexibility to microchimerism testing by enabling testing of recipients HLA-DR matched with their donors. However, the high level of sensitivity achieved with the technique (1:100,000) leads to a concomitant decrease in the specificity that results in the amplification of unexpected products, a phenomenon we encountered in the development of our nested PCR-SSP typing system for HLA class II alleles. We describe here how it is possible to compensate for these anomalies by including multiple testing of a pretransfusion sample that acts as a specificity control, establishing a rigorous baseline for subsequent analysis. (+info)
A partially agonistic peptide acts as a selective inducer of apoptosis in CD8+ CTLs.
(19/1082)
We have analyzed the effect of partially agonistic peptides on the activation and survival of CTL clones specific for a highly immunogenic HLA A11-restricted peptide epitope derived from the EBV nuclear Ag-4. Several analogues with substitutions of TCR contact residues were able to trigger cytotoxic activity without induction of IL-2 mRNA and protein or T cell proliferation. Triggering with these partial agonists in the absence of exogenous IL-2 resulted in down-regulation of the cytotoxic potential of the specific CTLs. One analogue selectively triggered apoptosis as efficiently as the original epitope, subdividing the partial agonists into apoptosis-inducing and noninducing ligands. Analysis of early T cell activation events, induction of Ca2+ influx, and acid release did not reveal significant differences between the two types of analogue peptides. These results demonstrate that some partial agonists can dissociate the induction of CTL death from CTL activation. Peptides with such properties may serve as useful tools to study signal transduction pathways in CD8+ lymphocytes and as therapeutic agents modulating natural immune responses. (+info)
Identification of natural antigenic peptides of a human gastric signet ring cell carcinoma recognized by HLA-A31-restricted cytotoxic T lymphocytes.
(20/1082)
Peptides of human melanomas recognized by CD8+ CTLs have been identified, but the nature of those of nonmelanoma tumors remains to be elucidated. Previously, we established a gastric signet ring cell carcinoma HST-2 and HLA-A31 (A*31012)-restricted autologous CTL clone, TcHST-2. In the present study, we determined the natural antigenic peptides of HST-2 cells. The purified preparation of acid-extracted Ags was submitted to the peptide sequencer, and one peptide, designated F4.2 (Tyr-Ser-Trp-Met-Asp-Ile-Ser-Cys-Trp-Ile), appeared to be immunogenic. To confirm the antigenicity of F4.2 further, we constructed an expression minigene vector (pF4.2ss) coding adenovirus E3, a 19-kDa protein signal sequence plus F4.2. An introduction of pF4.2ss minigene to HST-2 and HLA-A31(+) allogeneic tumor cells clearly enhanced and induced the TcHST-2 reactivity, respectively. Furthermore, when synthetic peptides of F4.2 C-terminal-deleted peptides were pulsed to HST-2 cells, F4.2-9 (nonamers), but not F4.2-8 or F4.2-7 (octamer or heptamer, respectively), enhanced the reactivity of TcHST-2, suggesting that the N-terminal ninth Trp might be a T cell epitope. This was confirmed by lack of antigenicity when using synthetic substituted peptides as well as minigenes coding F4.2 variant peptides with Ala or Arg at the ninth position of F4.2. Meanwhile, it was indicated that the sixth position Ile was critically important for the binding to HLA-A31 molecules. Thus, our data indicate that F4.2 may work as an HLA-A31-restricted natural antigenic peptide recognized by CTLs. (+info)
Identification of five MAGE-A1 epitopes recognized by cytolytic T lymphocytes obtained by in vitro stimulation with dendritic cells transduced with MAGE-A1.
(21/1082)
MAGE genes are expressed by many human tumors of different histological types but not by normal cells, except for male germline cells. The Ags encoded by MAGE genes and recognized by T cells are therefore strictly tumor-specific. Clinical trials involving therapeutic vaccination of cancer patients with MAGE antigenic peptides or proteins are in progress. To increase the range of patients eligible for therapy with peptides, it is important to identify additional MAGE epitopes recognized by CTL. Candidate peptides known to bind to a given HLA have been used to stimulate T lymphocytes in vitro. In some instances, CTL clones directed against these synthetic peptides have been obtained, but these clones often failed to recognize tumor cells expressing the relevant gene. Therefore, we designed a method to identify CTL epitopes that selects naturally processed peptides. Monocyte-derived dendritic cells infected with a recombinant canarypoxvirus (ALVAC) containing the entire MAGE-A1 gene were used to stimulate CD8+ T lymphocytes from the blood of individuals without cancer. Responder cell microcultures that specifically lysed autologous cells expressing MAGE-A1 were cloned using autologous stimulator cells either transduced with a retrovirus coding for MAGE-A1 or infected with recombinant Yersinia-MAGE-A1 bacteria. The CTL clones were tested for their ability to lyse autologous cells loaded with each of a set of overlapping MAGE-A1 peptides. This strategy led to the identification of five new MAGE-A1 epitopes recognized by CTL clones on HLA-A3, -A28, -B53, -Cw2, and -Cw3 molecules. All of these CTL clones recognized target cells expressing gene MAGE-A1. (+info)
A novel minor histocompatibility antigen recognized by HLA-A31 restricted cytotoxic T lymphocytes generated from HLA-identical bone marrow donor lymphocytes.
(22/1082)
Bulk cytotoxic T lymphocytes (CTL) were generated by in vitro stimulation of BMT donor lymphocytes with Philadelphia chromosome (Ph)-positive leukemic cells from an HLA-identical sibling patient. CTL were cytotoxic against the patient's leukemic cells as well as the EBV-lymphoblastoid cell line (EBV-LCL) generated from the patient's cells, suggesting that they recognize a minor histocompatibility antigen (mHAg). Subsequently, several CTL lines were established by a limiting dilution method and analyzed. One of these CTL lines, 16C12 CTL which used a single TCRbetaV3S1 for CD8 cells, lysed HLA-A31-positive leukemic cells and EBV-LCL, but not fibroblasts. The cytotoxicity against the patient's leukemic cells and EBV-LCL was blocked by anti-HLA-A31 moAb, anti-HLA-class I moAb, and anti-CD8 moAb, suggesting that this mHAg was presented with HLA-A31. The antigen recognized by 16C12 CTL seemed to be a novel mHAg, since HLA-A31 restricted antigen has not been reported to date and 16C12 CTL showed no cytotoxicity against EBV-LCL which probably express known mHAgs. CTL detecting this mHAg may play an important role in the GVL effect in HLA-A31-positive BMT patients. (+info)
Identification of a gene coding for a protein possessing shared tumor epitopes capable of inducing HLA-A24-restricted cytotoxic T lymphocytes in cancer patients.
(23/1082)
Genes encoding tumor epitopes that are capable of inducing CTLs against adenocarcinomas and squamous cell carcinomas, two major human cancers histologically observed in various organs, have rarely been identified. Here, we report a new gene from cDNA of esophageal cancer cells that encodes a shared tumor antigen recognized by HLA-A2402-restricted and tumor-specific CTLs. The sequence of this gene is almost identical to that of the KIAA0156 gene, which has been registered in GenBank with an unknown function. This gene encodes a Mr 140,000 protein that is expressed in the nucleus of all of the malignant tumor cell lines tested and the majority of cancer tissues with various histologies, including squamous cell carcinomas, adenocarcinomas, melanomas, and leukemia cells. However, this protein was undetectable in the nucleus of any cell lines of nonmalignant cells or normal tissues, except for the testis. Furthermore, this protein was expressed in the cytosol of all of the proliferating cells, including normal cells and malignant cells, but not in normal tissues, except for the testis and fetal liver. Two peptides of this protein were recognized by HLA-A2402-restricted CTLs and were able to induce HLA-A24-restricted and tumor-specific CTLs from peripheral blood mononuclear cells of most of HLA-A24+ cancer patients tested, but not from peripheral blood mononuclear cells of any healthy donors. These peptides may be useful in specific immunotherapy for HLA-A24+ cancer patients with various histological types. (+info)
Identification of a MAGE-2-encoded human leukocyte antigen-A24-binding synthetic peptide that induces specific antitumor cytotoxic T lymphocytes.
(24/1082)
Because MAGE-2 gene is expressed in a wide variety of malignant tumors and HLA-A24 is the most common allele in the Japanese population and is also frequently present in Caucasians, the identification of MAGE-2-encoded peptide presented by HLA-A24 is, therefore, considered to be important in order to develop specific immunotherapy for malignant tumors using peptides as a vaccine. By using a MHC-binding assay, eight peptides derived from MAGE-2 were found to bind with sufficient affinity to the HLA-A24 molecule. When the induction of specific cytotoxic T lymphocytes (CTLs) was examined using a simplified method, the highest human lymphocyte antigen (HLA) binder (EYLQLVFGI) in these peptides was able to elicit CTLs from unseparated peripheral blood mononuclear cells in HLA-A24 healthy donors by stimulation with freshly isolated, peptide-pulsed peripheral blood mononuclear cells as antigen-presenting cells and also by using interleukin 7 and keyhole-limpet hemocyanin in a primary culture. The induced CTL could, thus, lyse HLA-A24 tumor cells expressing MAGE-2, as well as the peptide-pulsed target cells, with antigen specificity in a HLA class I-restricted manner. The identification of this peptide may, thus, be of therapeutic value in peptide-based vaccines for the treatment of several types of malignant tumors expressing MAGE-2. (+info)