The initial reactions of graphite and gold with blood.

The initial reactions of graphite and gold with blood were investigated by short-time exposure to capillary blood and detection of surface-adsorbed plasma proteins and cells with an immunofluorescence technique. Antibodies specific to fibrinogen, complement factors C1q and C3c, prothrombin/thrombin, von Willebrand factor, and platelet- and leukocyte-membrane antigens were used. The fluorescence intensity was quantitated by computer-aided image analysis. Fibrinogen was the most abundant plasma protein immobilized on either surface, and dense populations of platelets adhered to the protein layer. Complement factors and prothrombin/thrombin were found on the graphite surface, localized in fibrin clots or related to platelets. Platelets were activated (expression of selectin CD62) on both surfaces but more extensively so on the gold surface. Activation of polymorphonuclear granulocytes (PMNGs), measured as expression of integrin CD11b, was seen on both surfaces but with different kinetics. On the graphite surface, the CD11b expression was only transient whereas on gold it increased with time. Our data indicate that graphite is more thrombogenic than gold but less inflammatory.