Immunological and histological studies of temporal arteries from patients with temporal arteritis and/or polymyalgia rheumatica.

Biopsies from the temporal arteries of 62 out of 80 patients presenting the clinical picture of temporal arteritis and/or polymyalgia rheumatica showed morphologically active or healed arteritis. Fifty-five of these biopsies revealed anti-IgG activity as measured by the mixed agglutination test. In 21 of the 27 cases which could be completely studied, the anti-IgG activity was connected with the presence of IgA, either alone, or together with IgG or IgM, or both, and complement. All of these 21 biopsies showed morphologically active granulomatous arteritis with signs of tissue destruction. In 6 biopsies, the active component appeared to be some type of Fc receptor in the tissue. Morphologically these biopsies showed either non-granulomatous mononuclear arteritis without definite necrosis or they represented various stages of healing arteritis with no or minor signs of tissue destruction. Weak anti-IgG activity was often found in a morphological type characterized by minimal inflammatory activity. These lesions are easily overlooked and the mixed agglutination test proved to be a good diagnostic tool in such cases. Arteries without anti-IgG activity showed no signs of active arteritis.