Immunohistochemical findings in cranial arteritis.

The cause of cranial arteritis is unknown, but the demonstration of immunoglobulin and complement in temporal artery biopsies by immunofluorescence suggest that it may be a disease of disordered immunity. Because of the inevitable problems of histologic interpretation associated with the fluorescent technique, 15 temporal artery biopsies from patients with active arteritis were examined by an immunoperoxidase method. Varying amounts of IgA, IgG, and IgM were identified in plasma cells and macrophages. Extracellular IgG was identified in 1 case, but there was no staining for complement. These findings provide no support for the concept of cranial arteritis as a form of immune complex vasculitis.