Purification of Wegener's granulomatosis autoantigen, proteinase 3, from neutrophils by Triton X-114 extraction of azurophilic granules

Defensin Interactions in Relation to Monoclonal and Disease-Related Proteinase 3 Antibodies Binding at the Catalytic Site

Proteinase 3 (PR3) is a neutrophil granulocyte enzyme and an autoantigen found in several forms of vasculitis. Due to the diagnostic and clinical importance of antibodies (Abs) to PR3, it is important to characterize the protein and the nature of its epitopes. Here, we have characterized PR3 monoclonal antibodies (MAbs) and disease-associated Abs and their dependency on the PR3 structure and modifications, especially interactions with α-defensins. Three MAbs (HYB 172-01, 172-04, 172-05), which bind to PR3 in its native and denatured forms and provide the disulphide bridges, were intact. α-1-antitrypsin (AT) binds to purified human neutrophil granulocyte PR3 and inhibits its proteolytic activity, towards a small synthetic peptide substrate and a large protein substrate (casein). AT also inhibited the binding of the three MAbs to PR3, indicating that they bind in a region affected by AT binding. However, the MAbs did not inhibit PR3 proteolytic activity with a small substrate, showing that they bound at the active site without restricting access to the substrate cleft. Patient-derived Abs showed essentially the same characteristics as the MAbs, with important implications for vasculitis diagnostics and pathophysiology. Current findings illustrate that PR3 epitopes depend on the three-dimensional structure of the PR3/defensin complex, and that the epitopes depend to a smaller or larger degree on PR3/defensin associations.

Neutrophil elastase, proteinase 3 and cathepsin G: physicochemical properties, activity and physiopathological functions

Polymorphonuclear neutrophils form a primary line of defense against bacterial infections using complementary oxidative and non-oxidative pathways to destroy phagocytized pathogens. The three serine proteases elastase, proteinase 3 and cathepsin G, are major components of the neutrophil primary granules that participate in the non-oxidative pathway of intracellular pathogen destruction. Neutrophil activation and degranulation results in the release of these proteases into the extracellular medium as proteolytically active enzymes, part of them remaining exposed at the cell surface. Extracellular neutrophil serine proteases also help kill bacteria and are involved in the degradation of extracellular matrix components during acute and chronic inflammation. But they are also important as specific regulators of the immune response, controlling cellular signaling through the processing of chemokines, modulating the cytokine network, and activating specific cell surface receptors. Neutrophil serine proteases are also involved in the pathogenicity of a variety of human diseases. This review focuses on the structural and functional properties of these proteases that may explain their specific biological roles, and facilitate their use as molecular targets for new therapeutic strategies.

Prevalence and clinical significance of antikeratin antibodies and other serological markers in Lithuanian patients with rheumatoid arthritis

OBJECTIVES

To assess the clinical value of several serological markers in Lithuanian patients with rheumatoid arthritis (RA) compared with control patients with rheumatic disease and age matched healthy controls.

METHODS

Serum samples from 96 patients with RA of approximately 8 years' duration, 90 rheumatic disease controls, and 37 healthy subjects were tested. Antikeratin antibody (AKA), antineutrophil cytoplasmic antibody (ANCA), and antinuclear antibody (ANA) titres were estimated by indirect immunofluorescence (IIF) and serum samples positive for ANA and ANCA were further studied by enzyme linked immunosorbent assay (ELISA). IgA and IgM rheumatoid factors (RF) were measured by ELISA.

RESULTS

A positive AKA test was highly specific for RA (diagnostic specificity 97%), being found in 44% of the patients. Although both RF tests had a higher sensitivity, they were less specific for RA. ANCA was detected in 33% of patients with RA but lacked diagnostic specificity. AKA and ANCA were associated with more erosive disease and the presence of extra-articular manifestations. Positivity for AKA, IgA RF, and ANCA was significantly associated with disease activity and worse functional capacity. However, in multiple regression analysis only positivity for AKA was significantly correlated with functional disability (p=0.0001), evaluated by the Steinbrocker functional classification, and no single marker had any relation with radiological damage.

CONCLUSION

Although AKA showed the highest disease specificity, all serological markers studied except ANA exhibited interesting associations with important clinical and paraclinical parameters of RA.

Surfactant cloud point extraction and preconcentration of organic compounds prior to chromatography and capillary electrophoresis

The use of preconcentration steps based on phase separation by the cloud point technique offers a convenient alternative to more conventional extraction systems. It has been used successfully for the preconcentration of species of widely differing character and nature, such as metal ions, proteins and other biomaterials, or organic compounds of strongly differing polarity. Here we address the most recent analytical applications of this methodology when used as an isolation and trace enrichment step prior to the analysis of organic compounds (polycyclic aromatic hydrocarbons, polychlorinated compounds, pesticides, phenolic derivatives, aromatic amines, vitamins, etc.) via liquid and gas chromatography or capillary electrophoresis.

Characterisation of autoantibodies to neutrophil granule constituents among patients with reactive arthritis, rheumatoid arthritis, and ulcerative colitis

OBJECTIVE

To study the frequency and distribution of antineutrophil cytoplasmic autoantibodies (ANCA) among patients with reactive arthritis (ReA), rheumatoid arthritis (RA), and ulcerative colitis (UC) using different immunological methods.

METHODS

Fifty serum samples from patients with reactive arthritis (26 with acute disease and 24 with chronic disease-that is disease of more than one year) were analysed for ANCA with indirect immunofluorescence, enzyme linked immunosorbent assay (ELISA) with six different neutrophil granule proteins as antigens, and immunoblotting on whole neutrophil extract and extracts of azurophil and specific granules. Thirty serum samples from patients with RA and UC served as controls in ELISA and indirect immunofluorescence.

RESULTS

Sixteen per cent of patients with ReA were positive in immunofluorescence compared with 30% of patients with RA, and 70% of patients with UC. Thirty two per cent of patients with ReA were positive in ELISA. Antibodies directed against lactoferrin occurred in 20%, antibodies against bactericidal permeability increasing protein (BPI), elastase, cathepsin G, myeloperoxidase, and proteinase 3 were found in 8%, 2%, 2%, 8%, and 6%, respectively. Overall, 50% of RA sera and 53% of UC sera were positive in one or more ELISA assays, the corresponding figures for antibodies against individual antigens were for RA 7%, 3%, 0%, 13%, 47%, 17% and for UC 13%, 20%, 0%, 23%, 10%, and 17%. In immunoblotting, bands corresponding to lactoferrin and BPI were recognised in 44% and 22% of ReA sera.

CONCLUSION

Antibodies against neutrophil granule antigens are often found in patients with ReA, primarily among those with chronic disease. The different methods detect various subsets of antibodies, with immunoblotting being the most and immunofluorescence the least sensitive.