Pharmacotherapy Newsletter

Volume 1, Issue 21, 06/08/2009

Question

What is the mechanism by which glucocorticoids (e.g., dexamethasone, methylprednisolone, prednisone) cause demargination of white blood cells (WBC) from the endothelium of blood vessels?

Answer

Part 2 of a 2 part series.  The factors that contribute to glucocorticoid induced leukocytosis (increase in white blood cell (WBC) counts) were described in part 1.¹  Of the mechanisms contributing to the increase in WBC counts, the demargination of neutrophils (polymorphonuclear leukocytes; PMN) from the endothelial lining of the blood vessels into the general circulation is most significant.²  In fact, approximately 61% of the increase in WBC counts comes from this biologic effect of glucocorticoid use and can be observed within 5-24 hours of initiation.^2-4  How do glucocorticoids (e.g., dexamethasone, methylprednisolone, prednisone) effect neutrophils (PMN) to cause this demargination?