IMMUNOPHENOTYPIC ANALYSIS OF THE AORTIC-ANEURYSM WALL SUGGESTS THAT VASCULAR DENDRITIC CELLS ARE INVOLVED IN IMMUNE-RESPONSES

Objective: Inflammatory infiltrates similar to those in atheroscleroti c plaques are prominent in the abdominal aortic aneurysm wall. Antigen presenting vascular dendritic cells are present in both early and adv anced atherosclerotic lesions but their possible participation in abdo minal aortic aneurysms has not been previously examined. This study re ports the presence of vascular dendritic cells in abdominal aortic ane urysms and their participation in immune responses. Methods: Samples o f the anterior wall were collected from 18 atherosclerotic infrarenal abdominal aortic aneurysms ranging in diameter from 5-8 cm, All the pa tients were operated upon electively and no ruptured or rapidly expand ing abdominal aortic aneurysms were included. Specimens were immediate ly frozen or fixed in 10% buffered formalin. Vascular dendritic cells were identified with anti-CD1a or with S-100. T cells and T cell subpo pulations were identified with anti-CD3, anti-CD4 and anti-CD8. B cell s were studied with anti-CD20, Analyses were carried out in sets of co nsecutive parallel sections immunostained with these antibodies and do uble immunostaining included different combinations of antigens such a s CD1a/CD3, S-100/CD4, S-100/CD8. Results: Most inflammatory infiltrat es were found in the adventitia. These infiltrates contained B cells ( CD20 +) and T cells (CD3 +) with their CD4 + and CD3 + cell subpopulat ions. In the aneurysm wall, CD1a + /S-100 + cells exhibiting dendritic appearance were detected and double immunostaining demonstrated that these vascular dendritic cells contained different lymphocyte populati ons including CD3 +, CD4 +, CD8 + and CD20 + cells. In some inflammato ry infiltrates, B cells (CD20 +) represented the predominant cell popu lation (60-80%). Double immunostaining demonstrated that. in these inf iltrates, vascular dendritic cells contacted CD20 + cells. Conclusions : vascular dendritic cells are involved in immune reactions in the ane urysm wall, and this process mostly occurs in the adventitia, Vascular dendritic cells contact both T cells and B cells. suggesting that the se vascular dendritic cells differ from other dendritic cells, subtype s of which associate with T cells (Langerhans cells, interdigitating c ells) and B cells (follicular dendritic cells). (C) 1998 The Internati onal Society for Cardiovascular Surgery. Published by Elsevier Science Ltd. All rights reserved.