Evaluation of fluorescent antinuclear antibody assays, Crithidia luciliae substrate, and single-stranded DNA-binding capacity in diagnosis of four rheumatic diseases

Comparison of antinuclear antibody and rheumatoid arthritis factor test results between two nearby hospitals

Antinuclear antibody and rheumatoid arthritis factor test results were compared between two nearby hospitals of approximately the same size but with different patient populations. There were dramatic differences in percentage of positive results, titers, and patterns (for antinuclear antibody tests) between the two institutions.

Assessment of class-specific antibodies against denatured DNA in patients with systemic lupus erythematosus

In this retrospective study 103 serum samples from 16 females with systemic lupus erythematosus (SLE), obtained during a mean follow-up time of 2 years, were investigated for the presence of anti-denatured [single-stranded (ss)] DNA antibodies of the IgG, IgM, and IgA classes. The anti-ssDNA antibodies were determined by an enzyme-linked immunosorbent assay (ELISA), and the results were expressed in three ways: as units derived from a single serum dilution and as two parameters, E and A, calculated from the dose-response curve, E being an estimate of the effective amount of antibodies and A a function of the reaction constant between the antigen and the antibody. The simultaneous occurrence of anti-ssDNA antibodies of all three immunoglobulin classes was seen most often in the patients with the shortest duration of the disease. Clinically active disease was found to correlate with high reaction constants of the IgA anti-ssDNA antibodies. There was also an association between the IgA anti-ssDNA antibody levels and the presence of nephritis. Great fluctuations in the amounts of effective antibodies of the IgG class were seen in seven patients, in six of whom changes in the disease activity also were seen. Changes in the disease activity were unaccompanied by fluctuations in the IgG anti-ssDNA levels in four patients; two of these patients were positive for antibodies against extractable nuclear antigens.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunoperoxidase assay for anti-dsDNA antibodies using Crithidia luciliae substrates

In studies on 779 fresh, unselected ANA+ sera, 50 (6.4%) were found to have anti-dsDNA antibodies, by using CIP (C. luciliae immunoperoxidase), and 84% of the 50 patients met the criteria for definite SLE. After freezing 36 of these sera for 13 +/- 1 months, only 52.8% were again positive by CIP. Using CIF (C. luciliae immunofluorescence), 16.7% and 52.8% of the same stored sera were anti-dsDNA+, with transmitted and epi-illumination, respectively. We favour CIP to CIF because: slide files are permanent, overcoming any lability of antibodies in frozen sera; kinetoplast, flagellum and nucleus are easily distinguished; perikinetoplast staining is avoided; specialized microscopic equipment is not needed.