Abstract 561: Role of Inflammatory Cells Activation in Growing Thrombus: Immunohistochemical Analysis of Aspiration Samples in Acute Coronary Syndrome
Introduction: Concerning the growing process of thrombus in acute coronary syndrome (ACS), recent studies suggested the participation of circulating inflammatory cells onto vascular wall incident. With immunohistochemical staining, tissues from thrombus aspiration therapy were analyzed.
Methods: Two hundred twenty consecutive samples obtained during emergency coronary angiography were studied. Samples were stained with hematoxylin and eosin, elastica van Gieson, and phosphotungstic acid hematoxylin. The sample area, white thrombus area (platelets and fibrin), and red thrombus area (red blood cells and fibrin) were measured. As antibodies in immunohistochemical staining, myeloperoxidase (MPO) expressed in activated neutrophils and macrophages, CD66b on activated neutrophils, and CD68 on macrophages, were employed respectively. In addition, immunohistochemical staining against P-selectin, tissue factor (TF) and PAI-1 were performed.
Results: One hundred and one samples included atheroma debris. In enlarged thrombus, red and white thrombi area ratio was correlated with the sample area (r=0.48, p<0.001). With immunohistochemical examination, granulocytes and macrophages were aggregated around the P-selectin positive platelets sharing the boundary between white and red thrombi. Abundance of MPO and CD66b expression were observed in neutrophils in this area. The percentage of MPO positive cell was significantly correlated with the sample area (r=0.50; p<0.001). TF immunostaining was observed in macrophages within atheroma and in neutrophils and macrophages within thrombi. PAI-1 immunostaining was also observed in neutrophils and macrophages within thrombi. Along the boundary between red and white thrombi, TF and PAI-1 immunostaining was coincident with MPO, CD66b and CD68 positive cells. Both the percentage of TF and PAI-1 positive cell in this area were significantly correlated with the sample area (r=0.43; p<0.001, r=0.60; p<0.001, respectively).
Conclusion: These results suggested activation of inflammatory cells occurred in growing thrombus tissue of ACS. Reciprocally with TF and PAI-1, enhanced activity of neutrophils may comprise considerable part of thrombus enlargement.