Adhesion of leukocytes to the aortic endothelium of conventional, specific pathogen free (SPF) and hypercholesterolemic SPF rats

Abstract

Adhesion of leukocytes to the aortic endothelium was studied in specific pathogen-free (SPF) and conventional rats and in SPF rats with diet-induced hypercholesterolemia. Nonspecific esterase activity with α-naphthyl acetate as substrate was used to characterize the adhered cells. Phagocytic activity was determined by injecting i.v. 0.1–0.4 ml/100 g doses of Monastral blue B® (MbB). Adhesion in SPF rats was 8 ± 4 esterase (+) cells/mm 2. Adhesion in conventional rats was of the same order except in 2 cases with antibodies to Mycoplasma pulmonis and Kilham rat virus, where adhesion was 44 and 68 esterase ( + ) cells/mm 2, respectively. For all MbB doses studied, phagocytic activity arose in a percentage of the adherent cells, ranging from 5 to 85%. Rats fed the hyperlipidic diet for 15 days developed severe hypercholesterolemia and adhesion was drastically increased to 200–700 esterase (+) cells/mm 2. Results indicate that: (1) spontaneous pathology in rats may produce an increased adhesion of leukocytes to the endothelium, and (2) phagocytic activity is only expressed in a fraction of the esterase (+) cells adhered to the endothelium.