In vivo and in vitro effects of dexamethasone on leukocyte migration in the rat adjuvant arthritis model

When polymorphonuclear leukocytes (PMNs) and mononuclear cells were isolated from the blood of dexamethasone-treated normal rats, in vitro mononuclear cell migration was inhibited and PMN migration was stimulated in comparison to controls. Inflammogen-induced PMNs showed inhibited cell migration due to dexamethasone treatment. Gamma camera imaging was then used to detect cells in vivo after labeling with indium-111. When the dexamethasone-treated blood cells were injected into adjuvant arthritis diseased rats, mononuclear cells showed depressed migration into the inflamed paws, while PMNs showed stimulated migration into the inflamed paws in comparison to controls. When the recipient adjuvant arthritic animals were treated with dexamethasone, both normal mononuclear cell and normal PMN migration to the inflamed paws were inhibited.