901-16 Leukocyte Activation with Platelet Adhesion After Coronary Angioplasty, a Mechanism for Recurrent Disease?

Increased expression of CD11b/CD18 (Mac-l) on monocytes (mono) and neutrophils (pmn) promotes their adhesion to endothelial cells. Thrombin activated platelets adhere to monos and pmns viaP-selectin. These complexes may affect the inflammatory process after coronary angioplasty (PTCA). During 10 elective single vessel PTCAs blood was obtained from femoral vein, coronary artery (Ca) and coronary sinus (CS) before and after PTCA. Two color flow cytometry with direct labeled monoclonal antibodies and isotype matched control antibodies was used to detect CD11b/CD18, L-selectin and platelets bound to monos and pmns. CD11b/CD18 expression increased after the procedure at all three sample sites on monos (p=0.001) and pmns (p=0.02). In each patient the increase in CD11b/CD18 on either cell type was similar (p=0.002, r=0.7). L-selectin shedding was not detected. Cytometric histograms showed 3 peaks of platelet fluorescence intensity on leukocytes. Before PTCA (pre) most leukocytes had few adherent platelets. The percentage of leukocytes with adherent platelets (*p=0.02) and the intensity of bound platelet fluorescence (↑p=0.02), i.e. the number of platelets per leukocyte, increased in samples from the Ca and CS after PTCA, despite standard aspirin and heparin therapy. In conclusion, leukocyte activation with platelet adhesion does occur after PTCA.Peak 1Peak 2Peak 3Peak 1Peak 2Peak 3Platelet fluorescence intensity on monosPercent total monosCa:pre25±8290±84539±27674±8%21±1%5±2%Ca:post27±7230±811072±390†64±2%19±9%17±7%*CS:pre19±6318±78602±29980±8%18±1%2±1%CS:post25±7293±80870±370†78±2%11±2%11±6%*Platelet fluorescence intensity on pmnsPercent total pmnsCa:pre12±2235±57529±27690±2%10±2%0.5±0.2%Ca:post17±2350±75946±253†84±3%13±3%4±2%*CS:pre12±2232±670±090±2%10±1%0%CS:post12±2296±80800±270†87±2%10±2%3±2%**p=0.02, †p=0.0