In vitro evaluation of cell-mediated immunity to Epstein Barr virus.

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.