High titers of autoantibodies in patients with sickle-cell disease.

OBJECTIVE: Frequency and titers of autoantibodies in patients with sickle-cell disease (SCD) have been reported as relatively high. In a prospective study of 88 patients, we examined this "hyper-autoreactivity" and its clinical consequences. METHODS: For 1 year, patients with SCD were screened for the presence in their serum of antinuclear, anti-double-stranded DNA, antiextractible nuclear antigens, anticardiolipin antibodies, and rheumatoid factors. A population of 85 sex-matched individuals of similar ethnic origin served as controls. RESULTS: Whereas prevalence of autoantibodies did not differ between the 2 groups, the type and rate of antinuclear antibodies were different. Autoantibodies from the SCD patients showed various immunofluorescence patterns, whereas only speckled patterns at low titers were present in controls. No antibody specificity was found in either group. SCD patients and controls displayed similar rates of anticardiolipin antibodies, but the SCD patients tended to be more frequently positive for rheumatoid factors. Six-year followup of the SCD patients did not provide any clinical evidence for onset of an autoimmune disease, except for 1 patient who developed rheumatoid arthritis, with increasing antinuclear antibodies followed by emergence of specific markers 5 years later. CONCLUSION: Patients with SCD displayed high titers of autoantibodies. This observation may be due only to immune activation and/or dysfunction in SCD, as neither pathogenic specificity of autoantibodies nor autoimmune clinical signs appeared in the majority of cases in our study.

Evaluation of the new multiplexed immunoassay, FIDIS, for simultaneous quantitative determination of antinuclear antibodies and comparison with conventional methods.

Our study was done to evaluate the FIDIS Connective kit (Biomedical Diagnostics, Marne la Vallée, France) for simultaneous quantitative determination in the same sample of 9 antinuclear antibody specificities directed against double-stranded DNA, SSA, SSB, Sm, Sm/RNP, Scl-70, Jo-1, ribosome, and centromere B and to compare it with standardized commercial methods, enzyme immunoassay and immunofluorescence. FIDIS technology constitutes a new multiplexed method using the Luminex 100 system (Luminex, Austin, TX) based on the use of distinct color-coded particles and flow cytometric detection. Serum samples from people with diagnosed rheumatic diseases with well-identified markers of autoimmunity were tested by a retrospective study. Specificity was assessed by testing blood donors and potential biologic interfering samples. This first evaluation demonstrated the analytic performance of FIDIS technology. Concordances with routine methods were between 99.1% and 100.0% on 222 samples. FIDIS was reliable (coefficients of variation < 10%) and accurate (correlation coefficients with enzyme-linked immunosorbent assay between 0.90 and 0.97) in a large measure range.