In vitro analysis of the Epstein-Barr virus: host balance in long-term renal allograft recipients.

Four indices of the EB virus carrier state, for which quantitative in vitro assays now exist, have been monitored in 55 renal allograft recipients under long-term immunosuppression, each patient being tested on a single occasion. By comparison with parallel data from healthy control donors, the results indicate the extent to which virus replication in the throat and virus-infected B cells in the blood are increased as a result of immunosuppression; the concordance between these two independent indices of the level of EB virus infection in vivo, first noted with healthy donors, was again observed within this large group of patients. Immunosuppression also leads to an impairment of virus-specific memory T-cell responsiveness and to an increase in anti-viral antibody titres, but the results show that the level of virus infection prevailing in any one individual cannot be inferred directly from these immunological indices of the virus:host balance. In allograft patients on stable levels of immunosuppression, virus and host appear to establish a new equilibrium. Limited prospective studies suggest that the position of this new equilibrium depends critically upon the virus:host balance prevailing in the same individuals before immunosuppression began. This may be an important consideration in identifying patients for whom immunosuppression may carry a particularly high risk of developing EB virus genome-positive lymphoma.