DEXAMETHASONE REDUCES CELL-SURFACE LEVELS OF CD11B ON HUMAN EOSINOPHILS

Overnight incubation of human eosinophils (Eos) with the glucocorticoi d hormone dexamethasone (DEX; 0.1 mu M) resulted in lower expression o f the CD11b, but not CD49d, antigen on their plasma membrane, as asses sed by flow cytometry, DEX produced a consistent inhibitory effect (ra nging from 16% to 20%) when tested at a concentration of 0.1 mu M. Eo stimulation with 100 ng/ml eotaxin produced an increase in CD11b (+26% ), but not levels and concomitantly a reduction on CD62L expression, T he inhibition exerted by DEX upon CD11b levels was also evident follow ing eotaxin upregulation, with a degree of inhibition similar to that seen on basal levels. These data highlight a novel mechanism of action by which glucocorticoid hormones may be effective in reducing Eo accu mulation during allergic inflammation in man.