THE INFLAMMATORY REACTION IN GIANT-CELL ARTERITIS - AN IMMUNOHISTOCHEMICAL INVESTIGATION

Objective: To assess the distribution of the inflammatory reaction in giant cell arteritis (GCA). Methods: Semiquantitative analysis on cryo stat sections stained with monoclonal antibodies against inflammatory markers. Results: The inflammatory infiltration was strongest in the a dventitia where it showed sharp demarcation along the enter border of the media. The endothelial immunopositivity for HLA-DR was strongest i n adventitial microvessels. The immunopositivity for macrophages, B-ce lls, HLA-DR, ICAM-1 and IL-2 was significantly stronger in the outer t han in the inner half of the intima. Conclusion: The distribution of i mmmunostainings and the crowding of cells seen at the outer media bord er indicates that the majority of the inflammatory cells enter the art erial wall from adventitial microvessels, migrate through the media an d that the cell migration and the inflammatory activity focuses on the peripheral intima/internal elastic membrane.