Reactivity of EBV Type A-Specific Cytotoxic T-Cells

EBV containing B lymphocytes are able to grow out spontaneously in vitro giving rise to immortalized lymphoblastoid cell lines (LCLs), whereas the proliferation of these cells in vivo is strictly controlled by specific HLA restricted cytotoxic T lymphocytes (CTL) (1)However, as EBV positive lymphocytes can be found lifelong in EBV positive individuals at a density of about one in 104 lymphocytes it is obvious that at least a small fraction of these cells is not recognized by CTL. Similarly tumour cells harbouring the virus can persist despite the existence of an active T cell response (2). At present we do not understand how these cells, i.e. either the normal or the malignant cells, are able to escape immune surveillance. One way for a better understanding of this phenomenon as well as of the immune mechanisms active in EBV infection in general is to study the interaction between CTL and EBV infected cells in vitro. In the approach presented here we established EBV carrying lymphoblastoid cell lines from several donors and used these cells for the generation of autologous EBV specific cytotoxic T cells. Here we characterize some of these cytotoxic T cell lines and clones specific for different substrains of type-A EBV.