AUTHOR=Sung Pil Soo , Park Dong Jun , Kim Jung-Hee , Han Ji Won , Lee Eun Byul , Lee Gil Won , Nam Hee Chul , Jang Jeong Won , Bae Si Hyun , Choi Jong Young , Shin Eui-Cheol , Park Su-Hyung , Yoon Seung Kew 

TITLE=Ex vivo Detection and Characterization of Hepatitis B Virus-Specific CD8+ T Cells in Patients Considered Immune Tolerant

JOURNAL=Frontiers in Immunology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2019.01319

DOI=10.3389/fimmu.2019.01319

ISSN=1664-3224

ABSTRACT=<p>In this study, we aimed to detect and characterize <italic>ex vivo</italic> virus-specific CD8<sup>+</sup> T cells in patients with immune-tolerant hepatitis B virus (HBV) infection. We investigated a Korean chronic hepatitis B cohort composed of 15 patients in the immune-tolerant phase, 17 in the immune-active phase, and 13 under antiviral treatment. We performed enzyme-linked immunospot (ELISpot) assays <italic>ex vivo</italic> and intracellular cytokine staining after <italic>in vitro</italic> culture. We also performed <italic>ex vivo</italic> multimer staining assays and examined the expression of programmed death-1 (PD-1) and CD127 in pentamer-positive cells. <italic>Ex vivo</italic> ELISpot revealed that HBV-specific T cell function was weaker in immune-tolerant patients than in those under antiviral treatment. <italic>In vitro</italic> culture of peripheral blood mononuclear cells for 10 days revealed that HBV-specific CD8<sup>+</sup> T cells produced interferon-γ in some immune-tolerant patients. We detected HBV-specific CD8<sup>+</sup> T cells <italic>ex vivo</italic> (using the HBV core<sub>18−27</sub> pentamer) in patients from all three groups. The PD-1<sup>+</sup> subset of pentamer<sup>+</sup> CD8<sup>+</sup> T cells was smaller <italic>ex vivo</italic> in the immune-tolerant phase than in the immune-active phase or under antiviral treatment. Interestingly, the proportion of PD-1<sup>+</sup> CD8<sup>+</sup> T cells in HBV-specific CD8<sup>+</sup> T cells correlated with patient age when all enrolled patients were analyzed. Overall, HBV-specific CD8<sup>+</sup> T cells are present in patients considered as immune-tolerant, although their <italic>ex vivo</italic> functionality is significantly weaker than that in patients under antiviral treatment (<italic>P</italic> &lt; 0.05). Despite the high viral load, the proportion of PD-1 expression in HBV-specific CD8<sup>+</sup> T cells is lower in the immune-tolerant phase than in other phases. Our results indicate appropriate stimulation may enhance the effector function of HBV-specific CD8<sup>+</sup> T cells in patients considered as being in the immune-tolerant phase.</p>