{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,20]],"date-time":"2026-08-20T14:32:32Z","timestamp":1787236352098,"version":"build-2736575974"},"reference-count":41,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,9,2]],"date-time":"2025-09-02T00:00:00Z","timestamp":1756771200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Immunol."],"abstract":"<jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>Epstein\u2013Barr virus (EBV) infects B lymphocytes and establishes lifelong persistence in the B cells. While systemic T-cell responses have been well characterized, the local immune response at the site of viral entry in children from undeveloped countries remains poorly understood.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Tonsillar CD4 and CD8 T cells in 32 pediatric patients undergoing tonsillectomy were classified as primary infected (PI), EBV carriers (EC), and non-infected children by serology. T-cell subsets were assessed by flow cytometry, whereas LMP1 and EBNA2 viral proteins were evaluated by immunohistochemistry.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>A higher percentage of activated HLA-DR+ CD8 T cells in PI patients was demonstrated. Notably, PD-1 expression was increased in both PI and EC, in particular in activated HLA-DR+ CD8 T cells. Positive correlations of EBNA2 with follicular helper T cells and Th1 cells, as well as a negative correlation between EBNA2 and activated CD8 T cells, were observed.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Discussion<\/jats:title>\n                    <jats:p>These findings suggest that, during asymptomatic primary infection by EBV, activated CD8 T cells are observed, but they may be cells that may exhibit features of exhaustion, which probably explains the absence of symptoms. PD-1 expression in CD8 T cells remains in EC. Additionally, Tfh, Th1, and CD8 T cells may influence the expression of EBNA2 and LMP1 latent viral antigens in tonsils.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fimmu.2025.1653165","type":"journal-article","created":{"date-parts":[[2025,9,2]],"date-time":"2025-09-02T05:34:16Z","timestamp":1756791256000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":3,"title":["Co-expression of PD1+ and HLA-DR+ in CD8+ T cells is increased in tonsils of children with EBV primary and persistent infection"],"prefix":"10.3389","volume":"16","author":[{"given":"Mar\u00eda Eugenia","family":"Amarillo","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karen","family":"Lindl","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Veronica","family":"Lapido","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ignacio E.","family":"Rojas Campi\u00f3n","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"M. 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