Cortisol resistant RPMI-1788 lymphocytes become sensitive to cortisol subsequent to a 24-h incubation period in medium containing purified human transcortin

Summary RPMI-1788 lymphocytes (a human cell line) are resistant to cortisol in vitro. Prior incubation for a minimum of 24 h a medium which contains purified human transcortin at a concentration of 50 g/ml renders these cells sensitive to the inhibitory action of cortisol as regards the synthesis of DNA. Only the transcortin-exposed cells contain a cortisol binding species whose sedimentation behavior in a sucrose gradient is identical to that of transcortin.This work was supported in part by grant ET-47 from the American Cancer Society. I thank Mr D. Pina and Dr R. Khaund for their excellent technical assistance.