title: HLA-DR expression in the vascular lesion and circulating T lymphocytes of patients with giant cell arteritis.
abstract: Giant cell arteritis (GCA) is a vascular inflammatory disease characterized by accumulations of T lymphocytes and macrophages in the arterial wall. In order to characterize the immune response in GCA, we have analysed temporal artery biopsies using a double-staining immunofluorescence method and studied T lymphocytes in peripheral blood with a fluorescence-activated cell sorter (FACS). HLA-DR was expressed on 28% (range 16-42%) of all T lymphocytes in the wall of the inflamed temporal artery, but only on average on 6% of peripheral blood T lymphocytes, indicating a high degree of local T cell activation in the inflammatory lesion. The proportions of T lymphocytes, T helper/inducer and T suppressor/cytotoxic cells in the blood of GCA patients before treatment with prednisolone did not deviate from those in normal individuals, but there was a minor increase in T helper cells after initiation of steroid therapy. The number of T helper cells expressing HLA-DR antigen and IL-2 receptor was not altered after 6-10 days of treatment with prednisolone. We found no evidence of HLA-DR expression by arterial smooth muscle cells in the GCA lesions, suggesting that these cells do not serve as antigen-presenting cells in GCA.
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005455:Fluorescent Antibody Technique; D013700:Giant Cell Arteritis / Q000188:drug therapy / Q000276:immunology*; D006684:HLA-DR Antigens / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000276:immunology; D011239:Prednisolone / Q000627:therapeutic use; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology*; D013699:Temporal Arteries / Q000276:immunology*
chemical_list: D006684:HLA-DR Antigens; D011239:Prednisolone