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Specific Cytotoxic T Lymphocytes (specific + cytotoxic_t_lymphocyte)

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Medical Sciences100%

Selected Abstracts

Phase I clinical trial using peptide vaccine for human vascular endothelial growth factor receptor 2 in combination with gemcitabine for patients with advanced pancreatic cancer

CANCER SCIENCE, Issue 2 2010
Motoki Miyazawa
Vascular endothelial growth factor receptor 2 (VEGFR2) is an essential factor in tumor angiogenesis and in the growth of pancreatic cancer. Immunotherapy using epitope peptide for VEGFR2 (VEGFR2-169) that we identified previously is expected to improve the clinical outcome. Therefore, a phase I clinical trial combining of VEGFR2-169 with gemcitabine was conducted for patients with advanced pancreatic cancer. Patients with metastatic and unresectable pancreatic cancer were eligible for the trial. Gemcitabine was administered at a dose of 1000 mg/m2 on days 1, 8, and 15 in a 28-day cycle. The VEGFR2-169 peptide was subcutaneously injected weekly in a dose-escalation manner (doses of 0.5, 1, and 2 mg/body, six patients/one cohort). Safety and immunological parameters were assessed. No severe adverse effect of grade 4 or higher was observed. Of the 18 patients who completed at least one course of the treatment, 15 (83%) developed immunological reactions at the injection sites. Specific cytotoxic T lymphocytes (CTL) reacting to the VEGFR2-169 peptide were induced in 11 (61%) of the 18 patients. The disease control rate was 67%, and the median overall survival time was 8.7 months. This combination therapy for pancreatic cancer patients was tolerable at all doses. Peptide-specific CTL could be induced by the VEGFR2-169 peptide vaccine at a high rate, even in combination with gemcitabine. From an immunological point of view, the optimal dose for further clinical trials might be 2 mg/body or higher. This trial was registered with ClinicalTrial.gov (no. NCT 00622622). (Cancer Sci 2009) [source]

A mutant HBs antigen (HBsAg)183,191 epitope elicits specific cytotoxic T lymphocytes in acute hepatitis B patients

CLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 3 2008
H.-G. Liu
Summary HBs antigen (HBsAg)183,191 (FLLTRILTI, R187 peptide) is a dominant human leucocyte antigen-A2 (HLA-A2)-restricted epitope associated with hepatitis B virus (HBV) infection in Caucasian populations. However, its prevalence is poorly understood in China, where there is a high incidence of HBV infection. In this report, we sequenced the region of HBsAg derived from 103 Chinese patients. Approximately 16·5% of the patients bore a mutant HBsAg183,191 epitope in which the original arginine (R187) was substituted with a lysine (K187 mutant peptide). Importantly, K187 still bound to HLA-A2 with high affinity, and elicited specific cytotoxic T lymphocyte (CTL) responses in HLA-A2/Kb transgenic mice. K187-specific CTLs were also generated successfully in acute hepatitis B (AHB) patients, indicating that this mutant epitope is processed and presented effectively. Our findings show that R187-specific CTLs can cross-react with the K187 peptide. These findings reveal that K187 still has the property of an HLA-A2 restricted epitope, and elicits a protective anti-HBV CTL response in humans. [source]

Safety of allogeneic Epstein,Barr virus (EBV)-specific cytotoxic T lymphocytes for patients with refractory EBV-related lymphoma

BRITISH JOURNAL OF HAEMATOLOGY, Issue 3 2002
Qi Sun
Summary. Epstein,Barr virus (EBV) causes lymphomas in immunocompromised individuals such as recipients of stem cell or organ transplants and patients with acquired immunodeficiency syndrome (AIDS). EBV has also been detected in the Reed,Sternberg cells of approximately 50% of all cases of Hodgkin's disease (HD). The purpose of this study was to examine the safety, and the clinical and immunological effects of infusing allogeneic EBV-specific cytotoxic T lymphocytes (CTL) for patients with refractory EBV-positive malignancies. In this pilot study, we have treated four patients with EBV-related lymphoma using allogeneic EBV-specific CTL. Two patients received EBV-specific CTL derived from partially human leucocyte antigen (HLA)-matched donors and the other two from HLA-matched siblings. No complications were observed as a result of the CTL infusions and all patients showed increased levels of EBV-specific CTL precursors (CTLp) post infusion. Of the two organ transplant patients, one had refractory disease and has sustained a complete remission following the T-cell infusions. The second has also been disease free since T-cell infusions, although the efficacy cannot be definitively attributed to CTL therapy because this patient received local radiation therapy prior to immunotherapy. A patient with AIDS-related, EBV-positive lymphoma had disease progression following CTL infusions. One HD patient received HLA 4/6 matched T cells from an unrelated donor and showed a decrease in the size of affected lymph nodes and resolution of B-symptoms post infusion. In conclusion, adoptive immunotherapy with allogeneic EBV-specific CTL is safe and mayhave efficacy in patients with high-risk or refractory EBV-related tumours. [source]

A mutant HBs antigen (HBsAg)183,191 epitope elicits specific cytotoxic T lymphocytes in acute hepatitis B patients

CLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 3 2008
H.-G. Liu
Summary HBs antigen (HBsAg)183,191 (FLLTRILTI, R187 peptide) is a dominant human leucocyte antigen-A2 (HLA-A2)-restricted epitope associated with hepatitis B virus (HBV) infection in Caucasian populations. However, its prevalence is poorly understood in China, where there is a high incidence of HBV infection. In this report, we sequenced the region of HBsAg derived from 103 Chinese patients. Approximately 16·5% of the patients bore a mutant HBsAg183,191 epitope in which the original arginine (R187) was substituted with a lysine (K187 mutant peptide). Importantly, K187 still bound to HLA-A2 with high affinity, and elicited specific cytotoxic T lymphocyte (CTL) responses in HLA-A2/Kb transgenic mice. K187-specific CTLs were also generated successfully in acute hepatitis B (AHB) patients, indicating that this mutant epitope is processed and presented effectively. Our findings show that R187-specific CTLs can cross-react with the K187 peptide. These findings reveal that K187 still has the property of an HLA-A2 restricted epitope, and elicits a protective anti-HBV CTL response in humans. [source]

Priming of hepatitis C virus,specific cytotoxic t lymphocytes in mice following portal vein injection of a liver-specific plasmid DNA

HEPATOLOGY, Issue 6 2000
Alexander Y. Lee
The immunology of hepatitis C virus (HCV) infection should be studied in the context of HCV antigen expression in the liver, because HCV primarily infects this organ. Indeed, the nature, function, and fate of T cells primed after antigen expression in the liver might differ from those primed when antigens are expressed systemically or in other organs, because the nature of the antigen-presenting cells (APCs) involved may be different. In addition, the normal liver contains a resident population of lymphocytes that differ from those present at other sites. Thus, we investigated whether HCV-specific CD8+ cytotoxic T cells (CTLs) could be elicited following portal vein (PV) injection of plasmid DNA in mice whose hepatic veins were transiently occluded. We show that PV injection of mice with "naked" DNA expressing the HCV-NS5a protein, under the control of a liver-specific enhancer/promoter, resulted in NS5a expression in the liver and the priming of HCV-specific CTLs. These results suggested that such a model might be relevant to the study of HCV-specific immune responses primed during natural infection. [source]