Anti-laminin auto antibodies in ANCA-associated vasculitis

Background. Endothelial cell damage occurs during vasculitic processes in v ivo. With the alteration of the endothelium, exposure to basement membrane components may occur with induction of humoral immunity. Methods. In the present study, we evaluated the prevalence of antibodies ag ainst the basement membrane antigen laminin (LMN) in patients with ANCA-ass ociated systemic vasculitis (AASV), pathologic controls (systemic lupus ery thematosus, mixed cryoglobulinaemia, Henoch-Schonlein purpura, primary glom erulonephritis) and normal individuals. Results. By ELISA, 21.6% of AASV (16/74) and 10% of pathologic controls (3/ 30), but only one of the normal controls (2.8%) had these antibodies (P = 0 .02). When AASV patients were divided into two groups according to diagnosi s and ANCA antigen specificity, antibodies to LMN were found in 27.5% of MP O-ANCA positive microscopic polyangiitis patients (11/40) vs only 14.7% of PR3-ANCA positive Wegener granulomatosis patients (5/34). There was no corr elation between the presence or titre of anti-ANCN antibodies and the main clinical and laboratory parameters. Conclusion. These results indicate that basement membrane antigens may beco me immunogenic in patients with AASV, especially in those with MPO-ANCA pos itivity. These antibodies are most likely the result of endothelial damage secondary to the initial inflammatory process but may well perpetuate furth er vascular damage in some patients.