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

Malaria Journal

Research

Yohan Kim¹  Bjoern Peters¹  Anette Stryhn²  Soren Buus²  Harini Ganeshan³  Thomas L Richie³  Jun Huang³  Sharina Reyes³  Maria Belmonte³  Martha Sedegah³  Judy Epstein³  Glenna Banania³  Christian F Ockenhouse⁴  Robert Schwenk⁴ 

[1] La Jolla Institute for Allergy and Immunology, La Jolla, CA, USA;Laboratory of Experimental Immunology, University of Copenhagen, Copenhagen, Denmark;Malaria Department, Infectious Disease Directorate, Naval Medical Research Center, 503 Robert Grant Avenue, 20910, Silver Spring, MD, USA;Malaria Vaccine Branch, Military Malaria Research Program, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD, USA;

关键词: Malaria;    CD8+ T cells;    MHC-I tetramers;    Activation markers;   

DOI  :  10.1186/1475-2875-12-376

 received in 2013-04-18, accepted in 2013-09-22,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundMalaria 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.MethodsFluorochrome-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.ResultsAnalyses by flow cytometry demonstrated that two of the six tetramers tested: TLDEMRHFY: HLA-A*01:01 and NEVVVKEEY: HLA-B*18:01, labelled tetramer-specific CD8+ T cells from two HLA-A*01:01 volunteers and one HLA-B*18:01 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.ConclusionsThe 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.

【 授权许可】

Unknown   
© Schwenk et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.