CHARACTERIZATION OF EXTRACELLULAR NUCLEOTIDE-INDUCED MAC-1 (ALPHA(M)BETA(2) INTEGRIN) SURFACE EXPRESSION ON PERIPHERAL-BLOOD LEUKOCYTES

Extracellular nucleotides, released during vascular injury, stimulate hematopoietic cells resulting in various physiological responses. We h ave determined that nucleotides can stimulate the expression of Mac-1 on peripheral blood leukocytes. ATP stimulated the expression of Mac-1 in a time- and dose-dependent manner with maximum expression occurrin g in 5 min at 10 mu M ATP. This increase in surface expression was obs erved in monocytes and granulocytes was dose-dependent and was compara ble in extent to the increase induced by the chemotactic peptide, form yl-Met-Leu-Phe. Other nucleotides including 2-MeSADP, ADP, UTP, and 2M eSATP had similar effect. Nucleotide-mediated stimulation of Mac-1 exp ression in granulocytes was completely inhibited by Ro-31-8220, a spec ific inhibitor of protein kinase C, while variable inhibition was obse rved in monocytes. These results demonstrate the stimulation of periph eral blood leukocytes by nucleotides causing an increased surface expr ession of Mac-1 which may be mediated by the activation of protein kin ase C. (C) 1997 Academic Press.