Detection of immune deposits in skin lesions of patients with Wegener's granulomatosis

Background-Wegener's granulomatosis (WG) is considered a pauci-immune syste mic vasculitis based on the absence of immune deposits in renal biopsies of patients with active disease. In animal models of antineutrophil cytoplasm ic antibody (ANCA) associated glomerulonephritis, immune deposits along the glomerular capillary wall are present at early stages of lesion developmen t. These deposits are degraded rapidly, resulting in "pauci-immune" lesions . Objective-To test the hypothesis that immune deposits can also be detected in early lesions of patients with WG, thereby initiating an inflammatory re action that, in time, is augmented in the presence of ANCA, resulting in pa uci-immune lesions later on. Methods-The presence of immune, deposits in skin biopsies taken within 48 h ours of lesion development was investigated. Direct immunofluorescence was used to examine 32 skin biopsies for the presence of immune deposits (IgG, IgA, IgM, C3c). When possible, a comparison was made between the immunofluo rescence findings in renal and skin biopsies, taken at the same time. Results-Four of 11 biopsies taken at initial presentation and four of 21 bi opsies taken at the onset of a relapse of WG showed IgG and/or IgA containi ng immune deposits in the subepidermal blood vessels. All nine renal biopsi es showed pauci-immune glomerulonephritis, irrespective of the presence (n= 5) or absence (n=4) of immune deposits in the skin biopsy. Conclusion-A sub stantial number of skin biopsies showed immune deposits during active disea se. These results could support the hypothesis that immune complexes may tr igger vasculitic lesions in WG.