Antinuclear Antibodies in Familial Mediterranean Fever

Two previous studies investigating double-stranded DNA titers in patients with familial Mediterranean fever uncovered conflicting results, in order to testify the reproducibility of the results revealed by one of these studies a high prevalence and correlation of double-stranded DNA antibodies with disease activity. We searched these antibodies using a commercially available enzyme immunoassay and also screened the fluorescent antinuclear antibodies by using substrate slides prepared with HEp-2 cell line to see whether there would exist any kind of antinuclear antibodies whatever. According to the cut-off value obtained by adding three standard deviations to the mean of healthy controls (n=36) there was not any statistically significant increase in double-stranded DNA values of patients with active disease (n=21). The percentage of fluorescent antinuclear antibodies in FMF group, healthy controls and lupus patients taken as positive controls (n=19) were 23.8%, 8.3%, 100%, respectively. The fluorescence intensity was extremely weak in negative controls and in FMF patients except one and could be defined as 'trace' when compared to that of lupus patients which was brightly luminescent. So, the prevalence of double-stranded DNA antibodies have not increased and there was not any significant difference between the percentage of fluorescent antibodies of FMF group and that of negative controls, although it appeared relatively high. This may be the result of female preponderance of our subjects, nonspecific binding of conjugate and subjective nature of assay deciding in borderline situations.