Steroid receptor-mediated modulation of CD4+CD62L+ cell homing. Implications for drug abusers

Naive human T cells home to peripheral lymph nodes via the leukocyte endothelial cell adhesion molecule-1 (LECAM-1, l-selectin, CD62L, Leu8 antigen) they express. We enriched populations of CD4+CD62L+ cells (attachment of Leu8+ T cells to flasks coated with anti-mouse IgG (AIS); Leu8+ T cells, 82.3% pure (+/- 2.3%), enriched for CD4+ cells by incubation over flasks coated with anti-CD4 antibody--this 3-4-day procedure yields an 88 +/- 1.4% recovery. Cells were treated with dexamethasone in vitro for 24-48 h, and monitored by flow cytometry. We found severe toxicity by this steroid at high concentration (10(-6) M: 35% decrease in CD62L+ T cells, 22% drop specifically in CD4+CD62L+ cells), suggesting the onset of receptor-mediated apoptotic events. The toxicity was dose dependent (5% and 7% drop in CD62L+ T and CD4+CD62L+ cells, respectively, at 10(-9) M, the concentration found in plasma 10 h following the administration of 1 mg dexamethasone). One mg of dexamethasone given to normal subjects leads to a 15-20% decrease in circulating CD4+CD62L+ cells at 10 h. This tends to be correlated with a drop in the number of glucocorticoid cytosolic receptors. Thus, steroids seem to modulate CD4+CD62L+ cell homing by means of receptor-mediated mechanisms.