GLUCOCORTICOID-INDUCED ANNEXIN-1 SECRETION BY MONOCYTES AND PERITONEAL LEUKOCYTES

1 We have studied the ability of the glucocorticoid, dexamethasone, to induce annexin 1 secretion by either human blood monocytes or rat per itoneal leukocytes. 2 The in vivo treatment of rats with dexamethasone (1.25 mg kg(-1)) selectively induced secretion of annexin 1 by perito neal leukocytes, as assessed by incubating these cells in culture medi um. Annexin 1 secretion was also induced in human cultured monocytes, in vitro, by 10(-6)M dexamethasone. 3 Annexin 1 secretion was inhibite d in the presence of 20 mM NH4Cl or by conducting the experiments at 1 8 degrees C. In contrast, it was not inhibited by monensin, nocodazole or brefeldin A. 4 The time necessary for annexin 1 synthesis and secr etion was less than 15 min. 5 These data indicate that glucocorticoids induce annexin 1 secretion by monocytes or peritoneal leukocytes. Bec ause it is not inhibited by monensin, nocodazole or brefeldin A and it is rapid, annexin 1 secretion seems to occur by the secretory pathway similar to that used by several cytosolic proteins such as interleuki n-1 beta.