Memory of Epstein-Barr virus-specific cytotoxic T cells in normal seropostive adults as revealed by an in vitro restimulation method.
Peripheral blood lymphocytes (PBL) from healthy adults responded with proliferation when stimulated in vitro with lymphoblastoid cell lines (LCL) transformed by Epstein-Barr virus (EBV). Proliferation was not dependent on EBV-serologic status of the PBL donors. After 4 times stimulation with the autologous LCL, viable cells recovered from the cultures consisted mainly of T cells in both EBV-seropositive and seronegative individuals. However, the effector functions of T cells from these 2 groups differed. The effector cells generated from PBL of the seropositive group were cytotoxic to autologous LCL cells, but those from the EBV-seronegative group showed little lysis against autologous LCL cells. These results indicate that the EBV-specific cytotoxic T cells (Tc) can be induced in vitro from seropositive but not seronegative individuals. On the other hand, EBV-nonspecific effector cells detected by K-562 target cell lysis were derived from cultures from both the seropositive and seronegative individuals, especially after the first and second stimulations. Lysis of K-562 targets decreased, however, after the third and fourth restimulation. In 56 effector-target combinations, EBV-specific Tc induced always lysed autologous LCL cells more effectively than allogeneic LCL cells. These data together with HLA-typing results suggested a possibility of the HLA-A or -B restriction of the EBV-specific Tc.