Soluble forms of the coinhibitory receptors programmed death 1 (PD-1) and Tim-3 exist, but their relationship with T-cell surface expression remains unclear. When measured by an enzyme-linked immunosorbent assay in plasma, soluble PD-1, and soluble Tim-3 were elevated during primary HIV infection, decreased on antiretroviral therapy to levels found in controls, and correlated with cell surface expression. We conclude that soluble PD-1 and soluble Tim-3 are easy to measure biomarkers of immune exhaustion which potentially eliminate the need for flow cytometry.
aNuffield Department of Medicine, University of Oxford
bNational Institute of Health Research Biomedical Research Centre, Oxford
cDepartment of Genitourinary Medicine and Infectious Disease, Guys and St Thomas’ NHS Trust
dChelsea and Westminster Hospital
eDivision of Medicine, Wright Fleming Institute, Imperial College
fImperial College National Institute of Health Research Biomedical Research Centre, London
gOxford Martin School, Oxford, UK.
*Eva Zilber and Genevieve E. Martin contributed equally to the article.
Correspondence to John Frater, Nuffield Department of Medicine, Peter Medawar Building for Pathogen Research, John Radcliffe Hospital, Oxford, UK. E-mail: email@example.com
Received 5 November, 2018
Revised 4 January, 2019
Accepted 15 January, 2019
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