Mobilizing Monocytes to Cross-Present Circulating Viral Antigen in Chronic Infection Adam J
Research article Mobilizing monocytes to cross-present circulating viral antigen in chronic infection Adam J. Gehring,1 Muzlifah Haniffa,2,3 Patrick T. Kennedy,4 Zi Zong Ho,1 Carolina Boni,5 Amanda Shin,3 Nasirah Banu,1 Adeline Chia,1 Seng Gee Lim,6 Carlo Ferrari,5 Florent Ginhoux,3 and Antonio Bertoletti1,7,8 1Infection and Immunity Programme, Singapore Institute for Clinical Sciences, Agency for Science Technology and Research (A*Star), Singapore. 2Institute of Cellular Medicine, Newcastle University, Newcastle, United Kingdom. 3Singapore Immunology Network, Agency for Science Technology and Research (A*Star), Singapore. 4Center for Digestive Disease, Blizard Institute of Cell and Molecular Science, Barts and The London School of Medicine and Dentistry, London, United Kingdom. 5Unit of Infectious Diseases and Hepatology, Laboratory of Viral Immunopathology, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy. 6Yong Loo Lin School of Medicine, National University of Singapore, Singapore. 7Program Emerging Viral Diseases, Duke-NUS Graduate Medical School, Singapore. 8Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. Selection of antigens for therapeutic vaccination against chronic viral infections is complicated by pathogen genetic variations. We tested whether antigens present during persistent viral infections could provide a per- sonalized antigenic reservoir for therapeutic T cell expansion in humans. We focused our study on the HBV surface antigen (HBsAg), which is present in microgram quantities in the serum of chronic HBV patients. We demonstrated by quantitative fluorescent microscopy that, out of 6 professional APC populations in the cir- culation, only CD14 monocytes (MNs) retained an HBsAg depot. Using TCR-redirected CD8+ T cells specific for MHC-I–restricted HBV epitopes, we showed that, despite being constantly exposed to antigen, ex vivo– isolated APCs did not constitutively activate HBV-specific CD8+ T cells.
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