Mg Huitema

Prevention of relapses in Wegener's granulomatosis by treatment based on antineutrophil cytoplasmic antibody titre

58 patients with biopsy-proven Wegeners granulomatosis (WG) were prospectively screened for clinical evidence of the disease 3-monthly, with antineutrophil cytoplasmic antibody (ANCA) measurements every month. Over 24 months, ANCA rose in 20 patients, 9 of whom were randomly assigned to receive combined 9 and 3 month courses of cyclophosphamide and prednisolone, respectively, at the time of ANCA rise; and 11 patients who were untreated except if there was a clinical relapse. 6 of 11 untreated patients relapsed within 3 months of ANCA rise. 3 of the remaining 5 patients relapsed after 3 months. There were no early or late relapses in patients randomised to treatment. Patients receiving no treatment at the time of ANCA rise took more cyclophosphamide and prednisolone than patients who were treated. Side-effects did not significantly differ between the two groups.

Predominance of IgG1 and IgG4 subclasses of anti-neutrophil cytoplasmic autoantibodies (ANCA) in patients with Wegener's granulomatosis and clinically related disorders.

In view of the supposed hypersensitivity, the elevated levels of IgE, and the occurrence of eosinophilia reported in Wegeners granulomatosis and related conditions, we studied the IgG subclass distribution of ANCA directed against a 29‐kD serine protease and myeloperoxidase (MPO) in 41 untreated ANCA‐positive patients with several forms of active vasculitis and/or glomerulonephritis. We found that both 29‐kD ANCA and MPO ANCA were predominantly of the IgG1 and IgG4 subclass in all groups of patients. The additional presence of IgG3 subclass was associated with renal involvement. We compared the subclass distribution of ANCA with that of total IgG subclass levels, and with the IgG subclass distribution of antibodies to cytomegalovirus (CMV) as a persistent endogenous antigen and antibodies to tetanus toxoid (TT) as an exogenous recall antigen. Total levels of IgG4 were elevated in the majority of the patients together with elevated IgG1 levels. Antibodies to CMV and TT, however, had the same subclass distribution as found in normals and did not show enhanced IgG4 expression. ANCA belong predominantly to the IgG1 and IgG4 subclass, which may suggest that the production of ANCA is related to recurrent exposition to the antigen(s) involved, possibly as part of a hypersensitivity reaction.

Levels of soluble VCAM-1, soluble ICAM-1, and soluble E-selectin during disease exacerbations in patients with systemic lupus erythematosus (SLE); a long term prospective study

Active SLE is characterized by immune deposits and subsequent vascular inflammation in many organs. Expression and up‐regulation of adhesion molecules is basic to migration of inflammatory cells into the tissues. Recently, soluble isoforms of these molecules have been described which might be an expression of their up‐regulation in the tissues and, as such, of disease activity. The purpose of this study was to evaluate whether changes in levels of soluble adhesion molecules reflect disease activity. We analysed serial sera in a 6‐month period preceding 22 consecutive exacerbations of SLE for levels of soluble vascular cell adhesion molecule‐l (sVCAM‐1). soluble intercellular adhesion molecule‐l (slCAM‐1), and sE‐selectin. Levels were related to clinical disease activity (SLEDAI). and levels of anti‐dsDNA and complement. At the time of maximal disease activity, levels of sVCAM‐1 in patients with SLE were higher than those in controls (P < 0.0001), levels in patients with renal involvement being higher than in those without (P < 0.02). Levels of sVCAM‐1 correlated with SLEDAI scores (P < 005) and, inversely, with levels of C3 (P = 0.01). In addition, in the presence of anti‐dsDNA, levels of sVCAM‐1 tended to correlate with levels of these autoantibodies (P < 0.1). Levels of sICAM‐1 were normal and sE‐selectin levels even decreased compared with controls. Levels of sVCAM‐l were higher at the moment of relapse (P = 0.001) than at 6 months before this time point. This rise correlated with the rise in SLEDAI score (P < 0.02). Levels of sICAM‐l and sE‐selectin did not rise, and remained in the normal range in all exacerbations studied. In conclusion, in contrast to sICAM‐1 and sE‐selectin, levels of sVCAM‐l are increased, rise parallel to disease activity during exacerbations in SLE, and are associated with decreasing levels of complement factors. This favours the hypothesis of immune deposit formation, activation of the complement cascade and activation of endothelial cells. Concurrent up‐regulation of vascular adhesion molecules may thus result in transmigration of activated inflammatory cells inducing tissue damage.

Elastase, but not proteinase 3 (PR3), induces proteinuria associated with loss of glomerular basement membrane heparan sulphate after in vivo renal perfusion in rats

Elastase, but not PR3, induces proteinuria associated with loss of glomerular basement membrane (GBM) heparan sulphate after in vivo renal perfusion in rats. PR3 and elastase are cationic neutral serine proteinases present in the azurophilic granules of polymorphonuclear leucocytes. Release of these proteolytic enzymes along the glomerular capillary wall may induce glomerular injury. Here, we investigated the effects of PR3 and elastase on the induction of proteinuria and glomerular injury after renal perfusion of these enzymes in Brown–Norway rats. Perfusion of active elastase induced a dose‐dependent proteinuria 24 h after perfusion, while inactivated elastase did not. Perfusion of comparable amounts of active PR3 did not induce proteinuria. Light and electron microscopy showed no morphological abnormalities in any experimental group. However, immunohistology revealed that proteinuria occurring after perfusion of active elastase was associated with a strong reduction in intraglomerular expression of the heparan sulphate side chain and, to a lesser extent, of the protein core of heparan sulphate proteoglycans (HSPG). In vitro, both elastase and PR3 digested HSPG. However, PR3 bound to a lesser extent to HSPG than elastase. We conclude that elastase, but not PR3, induces proteinuria after in vivo renal perfusion. This differential effect probably relates to different binding to the GBM of those enzymes due to differences in their isoelectric points. Degradation of heparan sulfate proteoglycans, leading to the disappearance of their side chains that contribute to the polyanionic structure of the GBM, appears to be involved in the induction of proteinuria after perfusion of elastase.

QUANTITATION OF ANTIBODIES TO NUCLEORIBONUCLEOPROTEIN BY ELISA - RELATION BETWEEN ANTIBODY-LEVELS AND DISEASE-ACTIVITY IN PATIENTS WITH CONNECTIVE-TISSUE DISEASE

We describe a solid-phase enzyme-linked immunosorbent assay (ELISA) for quantitation of antibodies to nucleoribonucleoprotein (nRNP/Sm). nRNP/Sm was purified from rabbit thymus acetone powder by immunoaffinity chromatography and characterized by counterimmunoelectrophoresis (CIE) and immunoblotting using sera with well-known specificities. The purified antigen was used in ELISA. Positive results in ELISA were obtained only in sera with anti-nRNP or anti-Sm specificity as determined in CIE. Levels of anti-nRNP/Sm as quantitated by ELISA were higher in the sera of patients with active connective tissue disease (n = 7) than in those with inactive disease (n = 6) (P less than 0.01). Differences in anti-nRNP/Sm levels were also found between patients with mildly active disease (n = 19) and those with active disease (P less than 0.01). Fluctuations of anti-nRNP/Sm levels related to disease activity were seen in longitudinal observation. Although anti-nRNP/Sm levels as quantitated by ELISA correlated with titres of antinuclear antibodies as determined by immunofluorescence (r = 0.46, P less than 0.05), quantitation of anti-nRNP/Sm by ELISA is superior since the assay is antigen-specific and its quantitation independent of titration-related inaccuracies.

IgG-mediated activation of leukocytes is independent of Fc-γ receptor polymorphism

Ligation of Fc-γ receptors for IgG (FcγR) can trigger potent effector cell responses. Genetic polymorphisms of these receptors modify IgG binding, and influence internalization of immune complexes. In patients with infectious or autoimmune diseases, skewing towards low-binding FcγR alleles has been demonstrated. The objective of this study was to investigate the influence of FcγR polymorphism on leukocyte activation.