Immunohistochemical characterization of inflammatory cells and immunologic activation markers in muscle and nerve biopsy specimens from patients with systemic polyarteritis nodosa.

OBJECTIVE

To investigate the phenotype of infiltrating cells in classic lesions of polyarteritis nodosa (PAN).

METHODS

Twenty-one muscle and 10 sural nerve biopsy samples from 24 patients with systemic PAN were studied using avidin-biotin-peroxidase and alkaline phosphatase-anti-alkaline phosphatase immunohistochemical techniques.

RESULTS

The inflammatory infiltrates consisted mainly of macrophages (41%) and T lymphocytes (41%), particularly of the CD4+ subset. Granulocytes were present in varying quantities (0-45%) and were more abundant in heavily infiltrated vessels and in those with fibrinoid necrosis. Dendritic cells could be identified in 4 samples. Proliferating and interleukin-2 receptor-expressing cells, present in 71% and 79% of the patients, respectively, were more frequent in untreated patients.

CONCLUSION

T cell-mediated immune mechanisms may play a role in the development and perpetuation of PAN lesions.