IS EBV PERSISTENCE IN-VIVO A MODEL FOR B-CELL HOMEOSTASIS

We have measured the absolute numbers of EBV-infected B cells in the p eripheral blood of healthy persistently infected individuals. Single m easurements on a panel of 15 healthy individuals demonstrate that the frequency varies over a wide range from 1-50 per 10(6) B cells. Repeat measurements over 1-3.5 years on several individuals whose frequencie s varied over a 10-fold range showed that the variation does not repre sent the fluctuation in the frequency that can occur within an individ ual; rather, the frequencies are specific to the individual. The frequ ency within an individual measured over time is stable and contributes less than 10% to the variance seen in the whole population. These mea surements suggest that the level of EBV-infected B cells is tightly re gulated and we propose that the same homeostatic mechanisms that regul ate the levels of normal B cells also regulate B cells latently infect ed with EBV.