Mechanism of CD11b down-regulation from phorbol myristate acetate stimulated polymorphonuclear neutrophils

ABSTRACT

To investigate the mechanism of CD11b down-regulation in phorbol myristate acetate [PMA] stimulated polymorphonuclear leukocytes [PMN]. Purified PMN were stimulated with PMA in the presence, or absence, of various enzyme inhibitors. Following stimulation, PMN CD11b expression was examined by flow cytometry and Western-blotting. The entire work was carried out at Liverpool University between the period of 1998 and 2001. Stimulation of PMN with PMA induced the down-regulation of CD11b by a mechanism involving a combination of an oxidant and a serine protease; most likely the primary granule derived elastase. The present study shows for the first time the cooperation of both oxidants and enzymes in the down-regulation of PMN adhesion receptors