A kinetic study of glucocorticoid-heparin interaction on the in vivo DNA-synthesis of mouse lymphatic organs.

The effect of glucocorticoids and heparin (in depot form) on the DNA-synthesis of thymus and spleen of mice was investigated by measuring (3H)dThd incorporation in a four day period. The kinetics of glucocorticoid action was similar whether the hormones were applied in 11 beta-hydroxy-, or keto-form and was characterized by a suppressive effect with a maximum on the first two days after administration. The suppressive effect of glucocorticoids proved to be more marked in the thymus than in the spleen. Heparin per se did not change thymidine incorporation into the lymphoid organs, but injected 3 hours prior steroid administration inhibited the suppressive effect of cortisone, but not that of hydrocortisone. In addition, heparin even reversed the suppressing effect of cortisone on splenic (3H)dThd uptake. The effects of heparin on glucocorticoid action could be only observed when the steroid was applied intraperitoneally. This observation and other data discussed suggest the involvement of peritoneal cells (macrophages) in glucocorticoid-heparin interactions on DNA-synthesis of lymphoid organs.