Immunohistologic and cytochemical studies of temporal arteritis.

Arteritic lesions from 14 patients with temporal arteritis were studied by cytochemical and immunohistochemical methods to identify the nature of the inflammatory cell infiltrate and to demonstrate immunoglobulin deposition. The infiltrating cells typically seen were histiocytes, giant cells, monocytes, and lymphocytes. The lymphocytes were mainly T cells and the majority of them were of the helper/inducer (Leu-3a) T cell subset, as indicated by monoclonal antibody reactivity. Immunoglobulin deposits on the internal elastica were identified in only 6 patients and neutrophils were either very sparse or absent. These findings are consistent with the hypothesis that cell-mediated immunity may be important in the pathogenesis of temporal arteritis.