Background : Epstein-Barr virus (EBV) is a ubiquitous virus in humans and latently infects B cells. In some individuals, however, EBV produces chronic active infection and causes life-threatening complications due probably to cytokinemia induced by EBV-infected T or natural killer (NK) cells. The role of EBV-encoded small RNAs (EBERs), which are commonly expressed in EBV-infected T and NK cells, is still unknown.
Methods : The plasmid coding EBERs was introduced into human T-lymphotropic virus-I-negative human T-cell lines in a site-directed manner, and stable transformants were established. The alteration of cytokine expression in EBERs-expressing transformants and the activation of the downstream signaling cascade from dsRNA were examined.
Results : Among three mother T-cell lines and their transformants, only the transformants from MOLT-14 cells (γδ T cells) expressed EBERs. EBERs-expressing MOLT-14 cells produced a larger amount of interleukin-10 than did the mother cell line. The phosphorylation of dsRNA-dependent protein kinase (PKR) and that of IκBα which act downstream of PKR, increased in EBERs-expressing clones.
Conclusion : The γδ T cell-specific production of IL-10 through EBERs expression might lead to modification of the role of γδ T cells, and might play a role in human immune diseases.