Long‐term T‐cell‐mediated immunity to Epstein‐Barr virus in man. II. Components necessary for regression in virus‐infected leukocyte cultures

Regression of EB-virus-induced transformation occurs exclusively in cultures of leukocytes from seropositive donors. Studies have shown that the strength of regression could be assayed in terms of the proportion of T cells which must be added to the autologous EB virus-infected T-cell-depleted population in order to establish regression in the culture. The in vitro regression phenomenon was strongly T-cell-dependent but did not require the presence of either monocytes or, as a potential antigenic stimulus, the residual viral envelope material on the surface of virus-infected B cells. The T-cell-depleted population from seropositive donors sometimes transformed (7/60 cultures) without the experimental addition of virus. Regression appeared to be independent of cytotoxic mechanisms involving anti-viral antibodies and not to be mediated by soluble factors released into culture medium.