[Cyclosporine A fails to prevent thymocyte death induced by ionizing radiation and hydrocortisone]

In experiments with albino mongrel mice the influence of cyclosporine A on thymocyte death in vivo under the effect of ionizing radiation and hydrocortisone has been investigated. The effect was assessed by the amount of soluble polydeoxynucleotides (PDN) that are formed in the cells. Dose dependence of the PDN yield and kinetics of their formation in thymocytes as well as electrophoretic mobility of PDN were studied after irradiation and the cyclosporine A treatment. Cyclosporine A was shown to have no effect on the thymocyte death induced by irradiation in vivo. The same results were obtained with hydrocortisone. Possible mechanisms of action of cyclosporine A on death of lymphocyte and proliferating cells are discussed.