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

Titanium sheets were exposed to whole blood, and the TiO2 surface was inves tigated regarding the presence of cells, receptor expression on adherent po lymorphonuclear (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 chemil uminescence, Surface coverage of erythrocytes (9% to 10%), granulocytes (9% to 14%), and platelets (1% to 4%) dominated during the first 2 hours of bl ood contact, PMN granulocyte adhesion to titanium was associated with a rap id decrease in L-selectin expression within 16 minutes. Initially Fc gamma III receptor (CD16) expression dominated on the adherent cells. After 30 mi nutes, a shift toward integrin expression (CDIIb) was found on the adherent cells. All investigated receptors were down-regulated within 1 hour of blo od-titanium contact, Attempts were made to inhibit the initial adhesion of PMN granulocytes to titanium by adding specific antibodies or 2,3-diphospho glyceric 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 respi ratory burst was detected from adherent PMN granulocytes residing on the Ti O2 surface. The cells were, however, able to mount a respiratory burst in r esponse to opsonized zymosan.