John A. Hardin

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In systemic lupus erythematosus, antibodies against double-stranded DNA are a major contributor to renal disease. We have previously demonstrated that the pentapeptide Asp/Glu-Trp-Asp/Glu-Tyr-Ser/Gly is a molecular mimic of double-stranded DNA. This sequence is also present in the extracellular domain of murine and human NMDA (N-methyl-D-aspartate) receptor(More)
OBJECTIVE To determine the range of antinuclear antibodies (ANA) in "healthy" individuals compared with that in patients with systemic lupus erythematosus (SLE), systemic sclerosis (SSc; scleroderma), Sjögren's syndrome (SS), rheumatoid arthritis (RA), or soft tissue rheumatism (STR). METHODS Fifteen international laboratories experienced in performing(More)
OBJECTIVE To determine the performance characteristics of enzyme-based immunoassay (EIA) kits for the detection of antinuclear and other autoantibodies of defined specificities. METHODS Nine manufacturers of EIA kits to detect antibodies of defined specificities participated in a study in which they received coded sera from the Centers for Disease Control(More)
The Ku protein is an autoantigen that consists of 70- and 80-kDa polypeptides. It associates with double-stranded DNA at free ends. In the present study, we examined the ability of anti-Ku antibodies to immunoprecipitate various structures from extracts of HeLa cells prepared at different salt concentrations. Under physiological conditions, these antibodies(More)
The RNP and Sm antigens recognized by lupus erythematosus antibodies are located on discrete particles containing single small nuclear RNA's complexed with proteins. The antigens Ro and La are also on ribonucleoproteins. The small RNA's in ribonucleoproteins with Ro are discrete, like those associated with RNP and Sm; in contrast, ribonucleoproteins with La(More)
Ku, also known as nuclear Factor IV, is an abundant nuclear DNA-binding protein which requires free DNA ends for the initial interaction with double-stranded DNA (dsDNA) and can bind at multiple sites along dsDNA in an energy-independent manner. Its function in vivo is unknown, but it has been implicated in both DNA replication and repair and in(More)
OBJECTIVE To define the fine specificity of the 10 reference sera used for determination of antinuclear antibodies (ANA) and ANA subsets which are available from the Arthritis Foundation (AF) and from the Centers for Disease Control and Prevention (CDC). METHODS AF/CDC sera were assessed by experienced laboratory staff, using indirect immunofluorescence(More)
The mechanism of interaction between the Ku autoantigenic protein, a heterodimer of noncovalently linked 70,000- and 80,000-dalton subunits, and DNA was studied using immunoaffinity-purified Ku protein and a 300-base pair EcoRI fragment from HeLa cell DNA. In the nitrocellulose filter-binding assay, the Ku protein bound 32P-labeled double-stranded DNA, and(More)
We have characterized the biochemical nature of the Ku protein, the antigen recognized by autoantibodies from certain patients with scleroderma-polymyositis overlap syndrome. From extracts of HeLa cells labeled with [32P]orthophosphate, anti-Ku antibodies precipitated a high molecular weight nucleic acid identified as DNA because of sensitivity to DNase I(More)
BACKGROUND Excessive activity of dendritic cells (DCs) is postulated as a central disease mechanism in Systemic Lupus Erythematosus (SLE). Vitamin D is known to reduce responsiveness of healthy donor DCs to the stimulatory effects of Type I IFN. As vitamin D deficiency is reportedly common in SLE, we hypothesized that vitamin D might play a regulatory role(More)