Accessing Epstein-Barr virus-specific T-cell memory with peptide-loaded dendritic cells

The conventional means of studying Epstein-Barr virus (EBV)-induced cytotox ic T-lymphocyte (CTL) memory, by in vitro stimulation with the latently inf ected autologous lymphoblastoid cell line (LCL), has important limitations. First, it gives no information on memory to lytic cycle antigens; second, it preferentially amplifies the dominant components of latent antigen-speci fic memory at the expense of key subdominant reactivities. Here we describe an alternative approach, based on in vitro stimulation with epitope peptid e-loaded dendritic cells (DCs), which allows one to probe the CTL repertoir e for any individual reactivity of choice; this method proved significantly more efficient than stimulation with peptide alone. Using this approach we first show that reactivities to the immunodominant and subdominant lytic c ycle epitopes identified by T cells during primary EBV infection are regula rly detectable in the CTL memory of virus carriers; this implies that in su ch carriers chronic virus replication remains under direct T-cell control. We further show that subdominant latent cycle reactivities to epitopes in t he latent membrane protein LMP2, though rarely undetectable In LCL-stimulat ed populations, can be reactivated by DC stimulation and selectively expand ed as polyclonal CTL lines; the adoptive transfer of such preparations may be of value in targeting certain EBV-positive malignancies.