Modulation of cellular annexin I in human leukocytes infiltrating DTH skinreactions

Based on our previous studies shelving endogenous annexin I being depleted from migrated neutrophils (PMN) in vitro, we have tested whether the levels of this glucocorticoid-regulated protein in PMN and mononuclear cells (PBM C) were modified after adhesion to endothelial monolayers in vitro and extr avasation into skin blisters in vivo. III vitro, annexin I levels were depl eted more significantly (-70%) in post-adherent PMNs than bl monocytes (-25 %) and lymphocytes (-50%, only in the positive fraction), In vivo, a signif icant time-dependent increase (approximately threefold, P < 0.05) in cell-a ssociated annexin I tvas measured in PBMCs recovered from the blisters, whe reas no significant changes were detected in extravasated PMNs, This,vas as sociated with annexin I release in the blister fluids (similar to 35 ng/mL) , whereas no detectable protein was found in matched-paired plasmas, In con clusion, we report for the first time an activation of the annexin I pathwa y during an ongoing experimental inflammatory response hi humans, which is differently regulated between PMNs and PBMCs.