The Effects of Corticosteroids on Thymocytes Monitored by ESR Spectroscopy
Licht, Norman J.
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One of the most drastic effects of corticosteroids is their action on the thymus. After administration of cortisone, there has been an observed ninety-five percent decrease in the thymic weight. Recent studies have been conflicting on the site of action of corticosteroids on T cells. Wira and Munch found that the steroids bind specifically to nuclear membranes while Waddell and Currie suggest that the steroids do not penetrate the cell membrane. It has been recently found that cholesterol changes the fluidity of liposomes, as viewed by electron spin resonance (esr) studies. It was the purpose of this project to monitor the effects of various corticosteroids on T cells via esr-spectroscopy. The results of my research project may be summarized in the following: (l) No effects of corticosteroids on murine thymocytes in short in vitro incubations were observed, utilizing esr and spin labeling techniques as monitors of membrane structure. (2) A profile of the thymocytic membrane found a rigid structure of fatty acids near the polar surface of the bilayer, which gradually became less rigid as the length of the fatty acid extended into the bilayer.(3)Hydrocortisone resistant and hydrocortisone sensitive thymocytes were characterized by esr spectroscopy, with the hydrocortisone resistant cells having a more rigid membrane structure than the hydrocortisone sensitive cells.