Objective: Although T and B lymphocytes accumulate in atherosclerotic lesions and play a key role in their growth, the mechanisms involved in the adhesion and recruitment of T and B lymphocytes by the lesions have not been resolved. The aim of this study was to compare T and B lymphocyte adhesion to atherosclerotic arteries and to test the role of VCAM-1 and ICAM-1.
Material and methods: T and B lymphocytes were labelled with red and green fluorescent dyes and incubated with freshly isolated aortas from apolipoprotein-E-deficient mice. In some experiments the aortas were pre-incubated with specific monoclonal antibodies. After washing, the adhering cells were detected by confocal laser scanning microscopy.
Results: The number of T and B lymphocytes that adhered to the aortic intimal surface was similar in both lesioned and non-lesioned areas and in the shoulder region of the lesions. However, the adhesion of T and B lymphocytes was significantly higher in the shoulder regions compared with the lesioned (p<0.0001) and non-lesioned areas of the aorta (p<0.0001). After pre-incubation of the aortas with antibodies against VCAM-1 or ICAM-1, the lymphocyte adhesions in lesioned areas were 42 % (p = 0.04) and 55 % (p = 0.17), respectively, of those in lesioned areas that had been pre-incubated with a control antibody. However, although VCAM-1 protein expression was most pronounced in the shoulder region, the lymphocyte adhesions in the shoulder region and in non-lesioned areas were unaffected by pre-incubation with VCAM-1 antibodies.
Conclusions: The results suggest that adhesion of T and B lymphocytes to mouse aortic endothelium is similar, is affected by lesion topology and is dependent on VCAM-1 expression over the core of atherosclerotic lesions.