Immunopathological studies of polyarteritis nodosa and Wegener's granulomatosis: a report of 43 patients with 51 renal biopsies.

Although it is generally considered that vasculitis of the polyarteritis nodosa (PAN) group and Wegener's granulomatosis (WG) is immune complex (IC) mediated, there are no simultaneous data on circulating IC, complement levels and deposits of Ig and complement in the kidney. Therefore we have performed a retrospective study of 43 patients suffering from PAN and WG. Ig glomerular deposits were uncommon and scanty, except in two patients with WG; C3 deposits were detected in 12 patients, whereas fibrinogen was constantly found when lesions were recent and active. Similar data were obtained for the renal vessel walls. Contrasting with these results, rheumatoid factors and cryoglobulins, suggestive of the presence of circulating IC, were detected respectively in nine of 39 and seven of 37 patients, and IC 'activity' assessed by the Raji cell assay and the Clq binding assay was found respectively in six of 17 and nine of 10 patients before treatment, and in none of 10 and five of seven patients in remission. Haemolytic complement activity and complement components were never decreased, but the C3d breakdown product of C3 was elevated in all the eight patients studied before treatment. Signs of persistent hepatitis B virus (HBV) infection were detected in five of 25 patients of the PAN group, whereas three of eight patients with WG had only anti-HBV antibodies. Furthermore, cytomegalovirus (CMV) could be isolated from the blood in a case of WG before the treatment was started. Persistent interferonaemia was detected in one of five patients. These results suggest either that renal deposition of CIC is transient, the paucity of Ig deposits being due to rapid clearance of IC by phagocytic cells; or alternatively that vascular and glomerular lesions are not caused by CIC, as in some cases of experimental vasculitis induced by infectious agents.