Expression of neutrophil and monocyte CD11B/CD18 adhesion molecules at different sites of the coronary tree in unstable angina pectoris

In the present study we measured CD11B/CD18 receptor expression of neutrophils and monocytes not only at the coronary ostium and in the coronary sinus, but also in the postobstructive chamber, immediately below the coronary stenosis, which was thought to be the culprit lesion of the unstable angina. Our findings demonstrate that neutrophils and monocytes from coronary sinus blood show a significantly higher expression of the CD11B/ CD18 adhesion receptors than leukocytes taken from the coronary ostium or the postobstructive chamber, whereas no difference was found in the adhesion receptorsʹ expression at the 2 latter coronary sites. These data favor the hypothesis that activation of leukocytes takes place at the microcirculatory interface with the injured myocardium, probably as a result of short but repeated episodes of myocardial ischemia. However, these findings do not contradict the hypothesis that an inflammatory process takes place within the unstable coronary plaque, as shown by a number of pathologic observations. 4,5,15,16 Our data concern only circulating leukocytes and show that neutrophils and monocytes are not activated during passage through the arterial narrowing responsible for the instability of angina but only in the distal part of the coronary bed.