Summary
The effect of hydrocortisone on six human lymphoblastoid cell lines was measured in relation to cell growth, number of Epstein-Barr (EB) virus antigen-positive cells, number of EB virus particles, and interferon synthesis. In two of the six cell lines (HRIK, MCI), hydrocortisone, in proportion to the dose, adversely affected cell viability concomitantly enhancing the expression of the EB virus genome. Recovery of normal viability in these two cell lines or lack of effect in the other three cell lines (EB3, Roswell Park Memorial Institute 1788, and AGI) appeared to be related to interferon synthesis. The observed effects occurred only in cell lines (HRIK, MCI) showing no detectable interferon prior to hydrocortisone, and recovery in these cell lines coincided with the appearance of detectable interferon. Conversely, in the three cell lines where interferon was either already present (AGI) or appeared within 3 days (EB3, Roswell Park Memorial Institute 1788), no adverse effect on cell viability and no definite activation of the EB virus genome could be demonstrated. In Raji, a few antigen-positive cells (4 to 23 per 105 cells) appeared but no viral particles. Cell viability was virtually unaltered and interferon was not detected. In Raji following bromodeoxyuridine (20 mg/ml) up to 1200 antigen-positive cells per 105 cells appeared with an associated interferon response. Priming of the HRIK cells with performed human interferon, 500 to 1000 units/ml of cell suspension for 72 hr or more prevented the adverse effect of hydrocortisone (20 to 100 µg/ml) on cell viability. These findings may help to reestablish a relationship between interferon synthesis and viral replication in EB virus-carrying lymphoblastoid cell lines.
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