Ex vivo tetramer staining and cell surface phenotyping for early activation markers CD38 and HLA-DR to enumerate and characterize malaria antigen-specific CD8+ T-cells induced in human volunteers immunized with a Plasmodium falciparum adenovirus-vectored malaria vaccine expressing AMA1.
Malar J
; 12: 376, 2013 Oct 29.
Article
em En
| MEDLINE
| ID: mdl-24168370
ABSTRACT
BACKGROUND:
Malaria is responsible for up to a 600,000 deaths per year; conveying an urgent need for the development of a malaria vaccine. Studies with whole sporozoite vaccines in mice and non-human primates have shown that sporozoite-induced CD8+ T cells targeting liver stage antigens can mediate sterile protection. There is a need for a direct method to identify and phenotype malaria vaccine-induced CD8+ T cells in humans.METHODS:
Fluorochrome-labelled tetramers consisting of appropriate MHC class I molecules in complex with predicted binding peptides derived from Plasmodium falciparum AMA-1 were used to label ex vivo AMA-1 epitope specific CD8+ T cells from research subjects responding strongly to immunization with the NMRC-M3V-Ad-PfCA (adenovirus-vectored) malaria vaccine. The identification of these CD8+ T cells on the basis of their expression of early activation markers was also investigated.RESULTS:
Analyses by flow cytometry demonstrated that two of the six tetramers tested TLDEMRHFY HLA-A*0101 and NEVVVKEEY HLA-B*1801, labelled tetramer-specific CD8+ T cells from two HLA-A*0101 volunteers and one HLA-B*1801 volunteer, respectively. By contrast, post-immune CD8+ T cells from all six of the immunized volunteers exhibited enhanced expression of the CD38 and HLA-DRhi early activation markers. For the three volunteers with positive tetramer staining, the early activation phenotype positive cells included essentially all of the tetramer positive, malaria epitope- specific CD8+ T cells suggesting that the early activation phenotype could identify all malaria vaccine-induced CD8+ T cells without prior knowledge of their exact epitope specificity.CONCLUSIONS:
The results demonstrated that class I tetramers can identify ex vivo malaria vaccine antigen-specific CD8+ T cells and could therefore be used to determine their frequency, cell surface phenotype and transcription factor usage. The results also demonstrated that vaccine antigen-specific CD8+ T cells could be identified by activation markers without prior knowledge of their antigen-specificity, using a subunit vaccine for proof-of-concept. Whether, whole parasite or adjuvanted protein vaccines will also induce {CD38 and HLA-DRhi}+ CD8+ T cell populations reflective of the antigen-specific response will the subject of future investigations.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Glicoproteínas de Membrana
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Antígenos HLA-DR
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Subpopulações de Linfócitos T
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Malária Falciparum
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Vacinas Antimaláricas
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Linfócitos T CD8-Positivos
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ADP-Ribosil Ciclase 1
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Ano de publicação:
2013
Tipo de documento:
Article