Adhesion receptors of polymorphonuclear granulocytes on titanium in contact with whole blood

Titanium sheets were exposed to whole blood, and the TiO2 surface was investigated regarding the presence of cells, receptor expression on adherent polymorphonuclear (PMN) granulocytes, and the ability of these cells to mount a respiratory burst when challenged with opsonized zymosan. The techniques used were immunofluorescence with computer-aided image analysis and chemiluminescence, Surface coverage of erythrocytes (9% to 10%), granulocytes (9% to 14%), and platelets (1% to 4%) dominated during the first 2 hours of blood contact, PMN granulocyte adhesion to titanium was associated with a rapid decrease in L-selectin expression within 16 minutes. Initially Fc gamma III receptor (CD16) expression dominated on the adherent cells. After 30 minutes, a shift toward integrin expression (CDIIb) was found on the adherent cells. All investigated receptors were down-regulated within 1 hour of blood-titanium contact, Attempts were made to inhibit the initial adhesion of PMN granulocytes to titanium by adding specific antibodies or 2,3-diphosphoglyceric acid (phospholipase D inhibitor) to blood before surface contact, Adding anti-CD16 resulted in a 67% reduction in cell adhesion, whereas a 35% reduction was found with 2,3-diphosphoglyceric acid. No spontaneous respiratory burst was detected from adherent PMN granulocytes residing on the TiO2 surface. The cells were, however, able to mount a respiratory burst in response to opsonized zymosan.