[Influence of dexamethasone on RNA synthesis in human peripheral blood lymphocytes].

Biphasic character of dexamethasone action on the lymphoid tissue is observed in the tissue culture of partially purified peripheral blood lymphocytes. Stimulation of the RNA synthesis occurred after 6-hour incubation of lymphocytes with the hormone. Sedimentation analysis of labeled RNA, fractionated in a column containing poly-U sepharose pointed to increase in the quantity of the messenger RNA and enrichment of the cytoplasmic RNA with poly-A sequences. At the same time the Mn++-dependable RNA polymerase sensitive to alpha-amanitin was activated. Inhibition of the RNA synthesis is observed after 24-hour cultivation of lymphocytes with the hormone. Biphasic effect of the steroid is also seen in the reaction of rosetteformation.