Elastase derived elastin peptides: putative autoimmune targets in giant cell arteritis.

Objective. Histological analysis of giant cell arteritis (GCA) reveals a granulomatous reaction around the internal elastic lamina. Elastolysis by multinucleated giant cells has also been reported. We investigated elastin derived peptides as putative recall antigens for peripheral blood mononuclear cells (PBMC) from patients with GCA. Methods. PBMC were collected from 17 patients with GCA (Group 1), 17 patients with vascular diseases, connective tissue diseases, or polymyalgia rheumatica without GCA (Group 2), and 17 healthy controls (Group 3). Cultures of PBMC with different elastin derived peptides or elastase were analyzed. Results. A proliferative response was obtained only with elastase derived elastin peptides in 12/13 untreated patients with GCA. Steroid treatment was believed to abolish this proliferative response in 4 patients with GCA. PBMC from only 3/34 non-GCA subjects responded to these antigens. No proliferative response was obtained for other elastin derived peptides or elastase in any subject. Conclusion. Degradation of native elastin by leukocyte elastase can provide elastin derived peptides that act as autoimmune targets for T cells in GCA.