ABSTRACT
This study was conducted to measure cell-mediated immune response in healthy Epstein Barr virus [EBV]-seropositive individuals using a tissue culture "growth inhibition" assay [regression assay] where peripheral blood lymphocytes [PBLs] were tested for their ability to inhibit the outgrowth of the autologous lymphoblastoid cell lines [LCLs]. Inhibition of the outgrowth of the autologous LCLs was seen after 4 weeks by the addition of PBLs from healthy EBV seropositive donors. The regression phenomenon was never seen when the donors of peripheral blood lymphocytes were EBV- seronegative. Regression assay showed that EBV- specific memory T cells were stable in healthy EBV seropositive over many years, which indicates the persistent nature of EBV infection