Autoimmunity and the kidney

Membranous glomerulonephritis induced in the pig by antibody to angiotensin-converting enzyme: considerations on its relevance to the pathogenesis of human idiopathic membranous glomerulonephritis

In the course of studies on the humoral consequences of swine to primate xenotransplantation, the investigators induced formation of glomerular subepithelial immune deposits and tubular lesions in pigs injected with heterologous antibody to angiotensin-converting enzyme. This study describes the morphology of the lesions, discusses their mechanism, explains their relevance for understanding the pathogenesis of human idiopathic membranous glomerulonephritis, and proposes future directions for investigations.

Renal biopsy in systemic lupus erythematosus: significance of glomerular thrombosis. Analysis of 108 cases

We investigated the frequency and distribution of glomerular thrombosis (GT) in 108 renal biopsies of lupus patients and correlated this finding with the presence of anticardiolipin antibodies (ACLA). GT was present mainly in the diffuse proliferative form. The activity index was higher in those patients with GT (12.9 +/- 4.7 vs 5.4 +/- 4.1, P < 0.01). The more severe histologic features, necrosis and extracapillary proliferation were also related with GT. In 18 cases with repeated biopsy the best predictors for the subsequent development of glomerular sclerosis were fibrinoid necrosis (P < 0.01), glomerular infiltration (P < 0.01) and an activity index of 10 or more (P < 0.05). GT also showed to be an important prognostic factor for sclerosis, although no statistically significant. ACLA were investigated in 36 patients at the time of renal biopsy. There were nine positive cases and in three of them this finding was related to GT. We can conclude that GT is a relevant feature showing active lupus nephritis and that it is not related to the presence of ACLA.

Immunoglobulin heavy chain switch region gene polymorphisms in glomerulonephritis

Much evidence suggests that primary IgA nephropathy (IgAN) and idiopathic membranous nephropathy (MN) are immune complex mediated diseases. Moreover, genetic factors may play an important role in their pathogenesis. Recently, restriction fragment length polymorphisms (RFLPs) of the immunoglobulin heavy chain genes have been described which appear to associate with glomerulonephritis. We have studied RFLPs of the switch region of the IgM (S mu) and IgA1 (S alpha 1) heavy chain in MN and IgAN. DNA obtained from British Caucasoids with IgAN (N = 75), MN (N = 43), and normal controls (N = 73), was digested with the restriction enzyme Sac1, and studied using Southern blot techniques and hybridization with a 32P labelled DNA probe homologous to S mu. This probe detects RFLPs at the S mu and S alpha 1 loci. The genotypic and allelic frequencies of the S mu and S alpha 1 alleles in IgAN and MN was similar to normal controls. Caucasoid subjects with IgAN from Northern and Southern Europe (Finland and Italy, respectively) were also studied to determine whether an ethnic variation in genetic susceptibility to IgAN exists. The frequency of the S mu and S alpha 1 alleles was similar between the patient groups and their respective local healthy controls. These results do not support the recent findings of an association with RFLPs of the S mu and S alpha 1 loci in IgAN and MN, and suggest that the immunoglobulin heavy chain switch region genes are not important in conferring disease susceptibility to IgAN or MN.

New strategies for plasma exchange in systemic vasculitis

The use of plasma exchange in the treatment of systemic vasculitis has been controversial and poorly defined. Since the discovery of anti-neutrophil cytoplasm antibodies (ANCA) and the demonstration of their specificity for systemic vasculitis, there has been a reassessment of the use of plasma exchange along the same lines as its use in anti-glomerular basement membrane disease. ANCA has also contributed to the diagnosis and classification of rapidly progressive glomerulonephritis, in which there is now firmer evidence to support the use of plasma exchange. Current work into the immunoregulation of ANCA by idiotype/anti-idiotype interactions is leading to new approaches to therapy and plasma exchange alone appears capable of inducing prolonged remission in some patients with vasculitis, possibly through an effect on these interactions.