Pathogenic principles in giant cell arteritis

In giant cell arteritis, an immune insult in the vascular wall initiates a reaction in the artery that leads to structural changes, intimal hyperplasi a, and luminal occlusion. The mechanisms triggering the immune stimulation are unknown; however, the process is strictly dependent on T cells that are found in the vicinity of the vasa vasorum in the adventitia and that produ ce interferon-gamma. The major effector cells in the artery are macrophages and giant cells that ape ultimately under T-cell control but assume differ ent functions depending on their location in the arterial wall. The respons e of the artery to the injury is maladaptive and includes mobilization and proliferation of smooth muscle cells in conjunction with matrix production and neoangionesis, resulting in the formation of a lumen-obstructive neoint ima. Heterogeneity in the immune insult and the resulting arterial response patterns correlate with variations in clinical disease. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.