Heterogeneous distribution of macrophages, tumour necrosis factor alpha, tissue factor and fibrinolytic regulators in atherosclerotic vessels.

Abstract

To assess the representativity of small vascular samples with regard to the expression of six important factors in atherosclerotic vessels. Circumferential frozen sections of iliac and femoral arteries (n = 9) from patients undergoing reconstructive bypass surgery. Immunohistochemistry with antibodies against macrophages (CD68), tumour necrosis factor alpha, tissue factor, tissue plasminogen activator, urokinase plasminogen activator and plasminogen activator inhibitor type 1. The distribution of these antigens was characterised by computer assisted image analysis. Antigen positive area in randomly chosen samples of varying size was compared with antigen positive area in the whole vessel transections. Marked heterogeneity was found with respect to the expression of these factors in atherosclerotic vessels. The representativity of samples was highly dependent on the size of the samples. PAI-1 was more evenly expressed compared to the other antigens. Estimates of the expression of these factors based on small samples from atherosclerotic arteries are unreliable.