Presentation of Epstein-Barr virus latency antigens to CD8+, interferon-γ-secreting, T lymphocytes

Epstein-Barr virus (EBV) infects more than 95 % of the human population and causes an asymptomatic life-long infection in the majority of EBV carriers. Cell-mediated immunity provides resistance to EBV, as demonstrated by the occurrence of EBV-induced post-transplant lymphoproliferative disease in immunosuppressed patients. Here we looked for IFN-gamma-producing T lymphocytes in the blood of healthy donors with a rapid enzyme-linked immunospot (ELISPOT) assay, comparing as antigen presenting cells monocytes and dendritic cells (DC) infected with recombinant vaccinia virus (rVV). We found a strong CD8(+) ELISPOT response to one or more of the EBNA 3A, 3B and 3C antigens in the PBMC from 14 / 18 donors. The sensitivity of the overnight ELISPOT assay was increased using DC as antigen-presenting cells, including 3 / 3 individuals who lacked ELISPOT in PBMC. In addition, DC could markedly expand EBV-specific spots after a 7-day culture. In a smaller number of donors, we documented recognition of the subdominant LMP 1, LMP 2 and EBNA 1 antigens that are expressed in a variety of EBV-associated malignancies. Therefore our data provide more evidence for the efficacy of DC in eliciting rapid responses to EBV latency antigens in circulating CD8(+) T cells.