Performance of Anti-Topoisomerase I Antibody Testing by Multiple-Bead, Enzyme-Linked Immunosorbent Assay and Immunodiffusion in a University Setting.

Background/objective: The criterion standard for anti-topoisomerase I antibody (anti-topo I antibody) testing in systemic sclerosis (SSc) uses immunodiffusion (ID) techniques, but enzyme-linked immunosorbent assay (ELISA) and multiple-bead technology are often used in current settings to save time and cost. Our aim was to assess the performance of the multiple-bead assay, ELISA, and ID testing methods.

Methods: We conducted a retrospective study of patients at the University of Michigan whose extractable nuclear antigen 10 autoantibody panel tested positive for the anti-topo I antibody by multiple-bead technology during a 1-year period.

Sensitivity and clinical utility of the anti-cytosolic 5'-nucleotidase 1A (cN1A) antibody test in sporadic inclusion body myositis: Report of 40 patients from a single neuromuscular center.

Sporadic inclusion body myositis (IBM) is the most common acquired myopathy affecting patients over age 50. The discovery of an autoantibody directed against a 43-44 kD protein (anti-cytosolic-5'-nucleotidase 1A or anti-cN1A) has provided support for the hypothesis of an immune-mediated pathogenesis. Previous studies have reported variable test sensitivity and specificity, and inconsistent results on the predictive value.

Development and evaluation of a standardized ELISA for the determination of autoantibodies against cN-1A (Mup44, NT5C1A) in sporadic inclusion body myositis.

Purpose: Sporadic inclusion body myositis (sIBM) is an autoimmune degenerative disease of the muscle, with inflammatory infiltrates and inclusion vacuoles. Its pathogenesis is not fully understood and the diagnosis is hampered by its imprecise characteristics, at times indistinguishable from other idiopathic inflammatory myopathies such as polymyositis and dermatomyositis. The diagnosis may be assisted by the detection of autoantibodies targeting Mup44, a skeletal muscle antigen identified as cytosolic 5'-nucleotidase 1A (cN-1A, NT5C1A).

Proteomic analysis of secreted proteins in early rheumatoid arthritis: anti-citrulline autoreactivity is associated with up regulation of proinflammatory cytokines.

Objectives: To identify peripheral blood autoantibody and cytokine profiles that characterise clinically relevant subgroups of patients with early rheumatoid arthritis using arthritis antigen microarrays and a multiplex cytokine assay.

Methods: Serum samples from 56 patients with a diagnosis of rheumatoid arthritis of <6 months' duration were tested. Cytokine profiles were also determined in samples from patients with psoriatic arthritis (PsA) and ankylosing spondylitis (n = 21), and from healthy individuals (n = 19).

Computer-assisted pattern recognition of autoantibody results.

Immunoassay-based anti-nuclear antibody (ANA) screens are increasingly used in the initial evaluation of autoimmune disorders, but these tests offer no "pattern information" comparable to the information from indirect fluorescence assay-based screens. Thus, there is no indication of "next steps" when a positive result is obtained. To improve the utility of immunoassay-based ANA screening, we evaluated a new method that combines a multiplex immunoassay with a k nearest neighbor (kNN) algorithm for computer-assisted pattern recognition.

Identification of polyclonal and monoclonal antibodies against tissue plasminogen activator in the antiphospholipid syndrome.

Objective: To test the hypotheses that some plasmin-reactive anticardiolipin antibodies (aCL) may bind to tissue plasminogen activator (tPA) and that some of the tPA-reactive aCL may inhibit tPA activity.

Methods: We studied the reactivity of 8 patient-derived monoclonal aCL with tPA and examined the presence of IgG anti-tPA antibodies in patients with the antiphospholipid syndrome (APS). The effects of the reactive monoclonal aCL on the activity of tPA were also examined.